Ottobuono de' Terzi, o Ottobono, è stato un condottiero italiano del XV secolo. Apparteneva al casato rurale dei Terzi di Parma. Era il primogenito di Niccolò Terzi il Vecchio e di madonna Margherita. Rimasto vedovo, a fine agosto del 1405, di una Orsini, il 1º di ottobre di quello stesso anno sposava nel castello di Dinazzano Francesca, figlia di Carlo da Fogliano. Ottobuono fu padre di Gio-Francesco, di Giberto (dal quale discese la famiglia dei Terzi di Sissa, e di Niccolò Terzi, il Guerriero.
Condottiero spietato, segnato da una fama sinistra, maturò le sue prime esperienze militari affiancando Giovanni Acuto. Combatté nel regno di Napoli agli stipendi di Antonio Acquaviva. Mise quindi le sue milizie al servizio della Repubblica di Venezia e al soldo di Giangaleazzo Visconti. Conte di Tizzano Val Parma e di Reggio Emilia, in tempi successivi e diversi fu infeudato marchese di Borgo San Giovanni e delle terre di Montecchio Emilia, Brescello, Colorno, Fiorenzuola d'Arda. Nel 1403 costituì una sua signoria su Parma, Piacenza e Reggio Emilia che tenne fino alla primavera 1409 quando i suoi avversari, coalizzati in una Lega guidata dagli Estensi, riuscirono infine a sopprimerlo.
Tra il 1393 e il 1397 combatté soprattutto nell'Italia centrale, dalle Marche dove lo si trova a Offida e alla difesa di Fermo da Antonio Aceti, alla Toscana e all'Umbria. Nel pisano affianca Alberico da Barbiano e Giovanni da Barbiano contro Bernardo della Serra e nel contrastare i fiorentini. Nel 1397, fallito un suo tentativo di avere San Miniato invade e devasta la Lucchesia e il contado fiorentino: compie razzie, incendia case e palazzi; uccide, fa prigionieri in previsione di riscatto. Fermato sul Serchio a San Quirico di Moriano, deve ritirarsi con Paolo Orsini e il Broglia. Ad agosto risale nel Mantovano e partecipa, come il padre Niccolò Terzi il Vecchio, alla prima battaglia di Governolo. Ha con Frignano da Sessa il comando della quinta schiera forte di mille cavalieri. Scaraventato al suolo da un colpo di lancia del Conte da Carrara, combatte a piedi con un'accetta, finché non è rimesso a cavallo dal Sessa, da Francesco Visconti e da Filippo da Pisa.
Nel maggio 1398 Gian Galeazzo Visconti rinnovò a Ottobuono la condotta. L'anno seguente, tornato in Toscana, a febbraio è con Facino Cane a Pisa a supporto della signoria di Gherardo d'Appiano, il fondatore della signoria di Piombino. Tre mesi dopo, a maggio, alleato a Fuzzolino Tedesco, Mostarda da Forlì e Astorre I Manfredi tornò nelle Marche al comando di 800 cavalieri e 1200 fanti inviati dai Bolognesi in appoggio a malatestiani e pontifici. A Cingoli contro la compagnia del Broglia e del Carrara viene sconfitto dopo nove ore di assalti.
A gennaio del 1400 entrò in Perugia accompagnato dal commissario visconteo Pietro Scrovegni, alla testa di 800 lance per sostenere il tentativo dei Raspanti e di Biordo Michelotti di trasferire la signoria della città al ducato di Milano. In quell'anno Ottobuono passò in Romagna, affiancando il Barbiano nell'assedio ad Astorre I Manfredi a Faenza. Più tardi lo si ritrova a Lucca dove offrì sostegno a Paolo Guinigi, che aspirava a quella signoria.
Nel 1401, a primavera, scende in campo a favore di Carlo Malatesta, percorre e devasta il Bolognese ai danni di Giovanni Bentivoglio, ma si ritira subito allorché s'affacciano in soccorso di questi i Carraresi e i Fiorentini. Tornerà a giugno, e assieme al Barbiano, ripetendo le razzie fino a San Lazzaro di Savena.
After a new expedition to Umbria, in Perugino, also in 1401 Ottobuono de 'Terzi gave excellent proof of his military capabilities, guiding the forces that prevented the passage of the troops of the emperor Robert of the Palatinate. Later he moved to Verona, quartered with his troops at the expense of the city.
In May 1402 Ottobuono is in Cento, in Emilia, sided at the battle of Casalecchio di Reno with the other Visconti leaders at the head of over twelve thousand men. The Terzi is in command, along with Prencivalle della Mirandola and Anderlino Trotti, of a deployment of 2,000 riders. During the summer the Terzi, once again allied to Barbiano, accompanied by the brothers Jacopo and Giovanni, returned to fight for the Visconti in Tuscany. The Duke, as a reward for his exploits, invested him with the castellanie, already belonging to Correggio, Colorno, Montecchio Emilia, Brescello, Boretto, Gualtieri and Cavriago.
In September 1402 Gian Galeazzo Visconti died suddenly. Ottobuono went without delay to Milan for the solemn funeral that took place in the Duomo. A few weeks later he was successfully engaged in the defense of Parma, assaulted by Pier Maria I de 'Rossi and Da Correggio. As a primary consequence of this victory, Ottobuono de 'Terzi became, in fact, the undisputed lord of Parma. He banished from the city, seizing their feuds, both the Rossi and the Correggio.
In the autumn Ottobuono moved to the head of 500 lances in Tuscany contributing to the offensive against Florence. In December, with a retinue of over 1200 knights and 300 infantrymen, Giannello Tomacelli, brother of Pope Boniface IX, drove from Perugia.
In January 1403, the Terzi occupied Assisi after defeating Paolo Orsini, Mostarda da Forlì, Carrara and Braccio da Montone.
In June Ottobuono at the head of 500 spears and 300 infantrymen was returning to Parma. He then attacked the Guelfi partisans in Reggio Emilia and Sassuolo, rooting everywhere in that territory.
In July 1403, the mother Duchess Caterina Visconti and her pupil, named Ottobuono de 'Terzi (flanked by his brother Jacopo) ducal commissioner for Parma, Piacenza, Reggio Emilia, Fiorenzuola d'Arda, Borgo Val di Taro, Pontremoli and Castell 'Arquato, Borgo San Donnino (Fidenza) In September, at the head of 300 cavalry and 200 infantrymen, he attacked the castles of San Secondo Parmense and Viarolo, and in those days reached an agreement with his rival Pier Maria I de' Rossi: In October, as a result of the new peace agreed, Rossi will return to Parma, whose members will be freed in the first days of November, while Terzi and Rossi are conspiring to remove Parma from the Visconti of which Ottobuono complained of considerable credit for the arrears of the proceeds.To redeem of these he succeeded in being confirmed by the Duke of Milan in 1404 the dominion over Parma and the investiture of Montecchio Emilia, Boretto, Brescello Gualtieri, B Orgo San Donnino and Fiorenzuola d'Arda The Terzi finally ordered all the inhabitants of the capital to return there, requiring them to swear loyalty to the Duke of Milan.
In January 1404 his forces together with those Pier de 'Rossi removed Montechiarugolo ai Correggio. In February Ottobuono together with Rossi became lord of Parma representing the Guelph party. The Ghibelline adversaries were expelled, the houses of the looted adversaries, the burnt prisons and archives thrown open. In March, the keys to the city and the fortresses were solemnly handed over to the Duomo of Parma to Ottobuono and Rossi.
In April Ottobuono obtained a supply of 700 lances in Lombardy. When Manfredi Scotti entered the city of Piacenza by encamping the pretext of defending the rights of Giovanni Maria Visconti, he was immediately expelled from the Terzi. These then, restless for the activism of Rossi, returned to Parma at the head of 600 men between knights and foot soldiers. Armed with the sanction of a new agreement with the Visconti, he annihilated the militia of the now former ally, seized bridges, doors and fortresses. Finally, sir of Parma is confirmed.
In May-June reconquest Reggio Emilia passed to the Estensi. Back in Parma, Ottobuono ordered the expulsion of all the male partisans of the Rossi and their relatives. So in Porporano the towers of the Catellani, the Guazzardi and the Valeriani, assaulted Alberi, Montechiarugolo and San Gemignano.
Florence with and the pope tried to intervene in the rescue of the Rossi, sending forces under the command of Paolo Orsini and Angelo Tartaglia, but Ottobuono reacted by issuing a new competition that also affected the women of that part, thus forced to leave Parma. In retaliation the Reds cut water to the city.
Meanwhile, the Terzi was invested by the Duke of Milan of the castle and the citadel of Reggio Emilia.
In September, Ottobuono returned to Parma to rage against the minor sons of the Reds and Guelphs, incarcerating all those who had completed five years and freeing them only with the issuance of a guaranty of 200 florins. To put an end to the persecution of the Reds, establishing a three-month truce, then intervened the papal legate Bartolomeo Cossa, with the Venetians and the Florentines.
The establishment of the noble regime in Parma by Ottobuono Terzi was once again recognized by the Visconti as a pledge, to be renewed one year for a year, against the payment of the arrears.
In October, with the green light of the Visconti, and always because of the balance of ducal debts to the leader, Ottobuono attacked Piacenza.
Still for the sake of money, where he only paid half a wage, I accept a new conduct proposed to him by the Republic of Venice on the battle against the Carraresi. [In November, with the Dal Verme, he seized the Chiusa di Ceraino north of Verona , of the fortress of Rivoli Veronese and erected an imposing bastide between Bussolengo, Pescantina and Castelrotto, then occupying Nogarole Rocca, Isola della Scala and, together with Dal Verme, Piove di Sacco.
In January 1405 he defeated the defenses of Verona near the Basilica of San Zeno, allowing the Venetians to conquer the towers of Porta del Calzari. Giacomo da Carrara fought with Francesco I Gonzaga and wounded him with a lance.
At the beginning of spring 1405 Ottobuono was in Milan. At the Parma government he left his brother Jacopo.
Together with Francesco Visconti took to the field against the Guelphs. When it was brought to the assault of Lodi, Pandolfo III Malatesta and Cabrino Fondulo came to the aid of Giovanni da Vignate, succeeding in taking possession of Piacenza thanks to the support of the local Guelphs. Informed, Ottobuono left the suburb of Lodi and, strong of 1000 riders and 1000 infantrymen, merged with the forces of Francesco Visconti and Facino Cane reconquering the city.
The Visconti, as always late with the money of the pipeline, renewed the investiture of Parma and Borgo San Donnino at Ottobuono. In July he returned to the siege of Lodi, but he soon abandoned him because of the disagreements with Francesco Visconti.
On August 10, Ottobuono's mother, Margarita, died in Parma. It was buried at three in the night in the friars Minor convent. On the 28th of the same month, his first wife, a Orsini, also died in Castelnuovo.
In September Ottobuono, with the brothers Giovanni and Jacopo, was added to the Venetian nobility.
On 1 October he celebrated his new marriage in the castle of Dinazzano with Francesca, daughter of Carlo da Fogliano.
During the months of October and November the conflict with the Pallavicini was rekindled. Ottobuono then built the bastions in Castione and Carabiollo.
The following month the Terzi will clandestinely participate in a conspiracy against the Dukes of Ferrara, helping Obizzo da Montegarulli. At the same time he will agree with Cabrino Fondulo to remove Cremona from Cavalcabò. In August he helped Giacomo and Pietro dei Rossi to reconquer the castle of San Secondo Parmense, from which they had been ousted by their relative.
Also in August 1406, Florence paid him 25,000 florins, committing him to refuse the defense of Pisa. In September Ottobuono resumed Piacenza at the Facino Cane, which had managed to seize it in April, then put it in a sack.
On 2 October, the duke of Milan, in return for the cancellation of his credit of 78000 florins, appointed Ottobuono count of Reggio Emilia, investing him also of Boretto, Brescello, Castelnuovo, Cavriago, Montecchio Emilia, Gualtieri, Campegine, Cogruzzo, Sant'Ilario d'Enza and Fiorenzuola d'Arda. A week later Ottobuono wrote to the Reggio regulators to give formal notice, ordering his coat of arms to be displayed with the Visconti viper in question. On behalf of Giovanni Maria Visconti he then entered into a truce with Carlo I Malatesta.
On 6 December 1406 his son Nicholas was born in Ottobuono, solemnly baptized at Christmas in the monumental baptistery of Parma in the presence of the most eminent personalities. 
1407 - In January he gives aid to Dal Verme against Facino Cane, putting in force a force of 7,000 men between soldiers and escapees of various localities. The following month passes the Po to Torricella and reaches the Bergamasco where it espouses Comun Nuovo, Spirano, Lurano, Brignano Gera d'Adda. Backed by the support of Colleoni, Pandolfo Malatesta, the Venetians and the papal legate Cossa, the Adda passes to Trezzo and reaches Vimercate. Conquest Desio, Saronno, Magenta and Rosate; advances beyond the Ticinello and beats in Morimondo with Facino Cane.
In the spring Ottobuono, allied with the Dal Verme, occupied Pavia. Reached Milan, besieged the Ghibellines barricaded in the castle of Porta Giovia. He then kills two of his bitter enemies, Giacomo and Francesco Grassi. The Twerzi would also demand the massacre of the Milanese Ghibellini, but found the firm opposition of Dal Verme who, exasperated, will try to remove him from Milan. Only in June, the Milanese will be able to get rid of them, paying them a hundred thousand florins.
In July Ottobuono was appointed Marquis of Borgo San Giovanni. He reconciled himself with the Pallavicini, to whom he returned the previously requisite possessions, while maintaining for himself the fortress of Borgo San Donnino. In August he renewed the agreements with the Duke of Milan, for the sake of which his armies will give themselves to piracy on the Po.  Always pressed by the need for money for the needs of his troops, he plundered the lands of Mirandola, San Felice sul Panaro and the Bassa Modenese up to Spilamberto and Vignola.
At the end of the year, all the assaults at the fortress of Piacenza failed, after returning to Parma, banning the most impetuous of the part of the Rossi who still survived in the city.
In 1408 began to coagulate in the various camps, increasingly influenced by the Estensi, all the feelings of exasperated aversion fueled by Ottobuono with his ruthless exploits. A hostile alliance was formed which was joined by the lords of Ferrara, Mantua, Brescia, Cremona, up to the hesitant Giovanni Maria Visconti, the Duchy of Milan, to whom were added the Rossi and the Pallavicini, the adversaries of all time.
In the spring of 1409, as a result of convulsive events and the succession of fighting, occupations, changes in the face accompanied by customary depredations, finally came to the conclusion of the tragic personal story of the leader Ottobuono de 'Terzi with the mortal ambush of Rubiera, differently narrated by historians.
In April he had received offers from Florence to pass in the pay of that Republic. At that time he repeated his assaults in the Modena area, the Rossi lands, in San Secondo Parmense, in Reggio Emilia.
In May Ottobuono with 1800 horsemen and 2000 infantrymen came out of Reggio, crossed the Secchia entering the county of Formigine to attack the forces of Niccolò III d'Este.
On the 27th of that month, it was Easter Monday, the proposal to meet the Marquis of Ferrara to negotiate an armistice arrived at the Terzi. The two met on the road between Modena and Pontalto, near a bridge that crosses the Via Emilia in the countryside of Rubiera. Niccolò d'Este hid his armies in a forest in the immediate vicinity. Ottobuono Terzi arrived at the appointment escorted by a hundred horsemen, with his inseparable advisor at the time, his father-in-law Carlo da Fogliano, his young son Niccolò, and Guido Torelli, lord of Guastalla and Montechiarugolo. The armies of the marquis of Ferrara, Niccolò III d'Este, accompanied by Uguccione Contrari, fiefdom of the Rocca di Vignola and Muzio Attendolo Sforza.
When the lord of Parma and the lord of Ferrara were engaged in the usual exchange of pleasantries, Sforza placed himself behind Ottobuono de 'Terzi and hit him prodigiously with a dagger, murdering him. The corpse, loaded then on a vil cart, was brought to Modena, and here dismembered amendment. Ottobuono's head, hoisted on a pike, was exposed in front of the Modena cathedral and then to the fortress of Felino.
Carlo da Fogliano, fleeing on foot, managed to rescue the very young son of Ottobuono, and his nephew, Nicholas within the walls of Parma. Here Giacomo Terzi, brother of Ottobuono, will proclaim the boy, who will become the fame of leader like Niccolò Terzi, the warrior, lord of the city. It will only cover that charge for twenty days.