Thieves were one of the available factions-for-hire during the Renaissance, alongside courtesans, mercenaries and the Romani. They were adept free-runners, and possessed a number of guilds in different cities; several of these, including the Venetian and Roman guilds, were allied to the Assassin Order. As such, they possessed a measure of virtue, in that they refused to steal from the poor and fought to defy the local, corrupt nobility.
However, a number of thieves were independent of the Order. In particular, the Cento Occhi were allied to the House of Borgia, and sought to counteract the Assassins; unaffiliated pickpockets chose to steal freely as well.
From as early as when a thief helped to save his life by urging him to run from the guards at his family's execution, Ezio Auditore da Firenze both helped and enlisted aid from thieves on several occasions.
Thieves were often included in the most well-informed factions of the cities, for which they were able to provide Ezio with information on assassination targets and other events in their district. In Florence in 1478, La Volpe made use of one of his thieves to lure Ezio to him, after which he gave the young nobleman details on how to locate Francesco de' Pazzi.
In 1481, after assisting Rosa, one of the members of the Venetian guild, Ezio allied with the thieves there in order to infiltrate the Palazzo della Seta. Together, he and the Venetian thieves successfully claimed the building after Ezio assassinated Emilio Barbarigo in 1485.
Some time prior to 1499, Paganino, a member of the Venetian guild, betrayed his allies and became a spy for the Templars; passing them vital information on the Assassin Order and their base in Monteriggioni. At the opening of the new year in 1500, his actions eventually led to the fall of Monteriggioni.
Upon traveling to Rome, Ezio allied his newly-founded Assassins guild with La Volpe's thieves. After aiding them in establishing their headquarters in La Volpe Addormentata, he learned of their close rivalry with the Cento Occhi thieves.
In contrast to the Assassin-allied thieves, the Cento Occhi stole from the poor, and terrorized the civilians of Rome. At La Volpe's request, Ezio assisted in repressing them, fighting in brawls alongside La Volpe's thieves, sullying the Cento Occhi's reputation with the Borgia, and killing the guild's leaders.
In 1511, Ezio visited the Constantinople Thieves Guild and learned they were having troubles due to a snitch tipping off the city guards to their activities. After an investigation into these claims, Ezio learned that a lord by the name of Halim was bribing the snitch, before assassinating the former.
Though he usually worked alongside the guilds to suppress Templar control of a city, Ezio also hired thieves on the streets, offering them money in return for assistance. Unlike the other hired factions, they could easily follow the Assassin along rooftops.
The thieves could help Ezio by distracting any soldiers guarding high-profile locations, such as banks or other restricted areas. They often did so by attacking or taunting the men, and subsequently luring them away. Should Ezio engage in a fight as they followed him, they would always help him defeat his enemies as well.
Thieves were lightly armed, carrying only a dagger (or a sword on rare occasions) and wearing very light armor. This allowed them to follow Ezio in many of his acrobatic moves, though did not offer much protection in combat.
To offset this, thieves resorted to speed and agility in combat, dodging and countering enemy blows much like Agile guards. As such, they were usually only vulnerable to well-protected guards, predominately Brutes and Seekers.
- The Steal Home achievement was awarded for winning a race against any thief in Assassin's Creed II. Also, in Assassin's Creed: Revelations, once Ezio fulfilled the guild challenges for the thieves and unlocked the capability for them to loot dead bodies, the Fast Fingers achievement could be unlocked after 50 instances of a hired group of thieves looting the dead bodies of guards.
- In the memories "Cleaning House," and "Who's Got Mail?", thieves used swords as opposed to short blades.
- Like guards, in Assassin's Creed II, thieves were generally better equipped in Venice than in Florence.
- The child in the mission "Human Cargo" was dressed like a thief.
- In Assassin's Creed: Brotherhood, Ezio could lock onto thieves that signaled the start of a thief assignment and perform execution moves on them. However, after appearing to die, they would soon recover and get back up.
- In Assassin's Creed: Project Legacy, it was possible to train Cento Occhi thieves and use them in missions.
- In Assassin's Creed: Lineage, the courier intercepted by Giovanni Auditore was dressed similarly to a thief.