The Cooper Clan is the most successful lineage of master thieves in history. Numerous grand heists have been performed by various Coopers, occasionally by assembling other thieves and experts of their fields around them to form a Cooper gang.
Notably, the Cooper Clan is also one of the most honorable lineages of thieves; Coopers steal only from those undeserving of what they possess, due to underhanded dealings or more sinister arrangements. A pervasive code of honor binds each Cooper, as the general ethos of a Cooper heist is to deprive the real criminals of their possessions — there is "no honor, no challenge, no fun in stealing from ordinary people." As INTERPOL Inspector Carmelita Fox puts it, the Coopers and the police work towards the same goal on different sides of the law. The Cooper Clan often clashes with criminal organizations due to its honor code, including the Fiendish Five and the Klaww Gang. They have also had encounters with rival thieves, such as Clockwerk or the Le Paradox clan.
- Sly Cooper – The most recent master thief, Sly is the son of an honorable Cooper that went down fighting while protecting his family and the Thievius Raccoonus. After the death of his parents, Sly was placed in an orphanage where he met his pals, Bentley and Murray, who he would later create their own Cooper Gang with. He defeated Clockwerk and Cyrille Le Paradox, two major enemies of the Cooper Clan. He also defeated Neyla, a corrupt INTERPOL agent who planned on becoming immortal, and Dr. M, a member of his father's gang who attempted to steal the fortune within the Cooper Vault.
- Bob Cooper – The first known Cooper, Bob was a thief from Gungathal Valley circa 10,000 BC. He stole pterodactyl eggs as food for his tribe. His major contribution was the invention of the tool that became the very first cane. His special ability was being able to climb on icy surfaces. He could not do common Cooper moves such as the Ninja Spire Jump or Rail Walk.
- Slytunkhamen Cooper I – Sly's ancestor from ancient Egypt circa 1350 BC, he was the father of Slytunkhamen II and the creator of the Thievius Raccoonus. His signature ability was to turn invisible to aid in stealing from corrupt pharaohs and greedy noblemen. He was the first known ancestor before the Cooper Gang's escapades in the Ice Age.
- Slytunkhamen Cooper II – Sly's ancestor from ancient Egypt circa 1300 BC and supposed creator of the Cooper Vault. He had two canes that bore a striking resemblance to the Egyptian Khopesh. He was skilled at creating the traps that were used in ancient Egyptian tombs.
- Salim al-Kupar – Sly's ancestor from middle age Arabia, who was an old man by 1001 AD. Salim was said to have the stealth of forty thieves, and was also a member of an organization of master thieves called the Forty Thieves. His weapon was a curved, hooked blade sporting a scimitar-like look, but with a much thicker blade. He perfected the climbing technique by creating a move called the Climbing Cobra, which he did not add to the Thievius Raccoonus. He owned a magic flying carpet and loved to eat.
- Sir Galleth Cooper – Sly's ancestor from medieval England circa 1301 AD. He was an honorable knight and cunning thief who fought with a lance featuring a hook point. He perfected the wall hook climbing technique by creating a barrier-smashing move called the Catapult Crash, which was not added to the Thievius Raccoonus.
- Slaigh MacCooper – Sly's ancestor from Scotland. The strongest of all of the Coopers, he could break any lock with a single blow using his large stone cane. He was the Cooper who created the wall edge move.
- Rioichi Cooper – Sly's ninja ancestor from feudal Japan circa 1603 AD. He created the Ninja Spire Jump and implemented Japanese artwork of himself in his part of the vault. His weapons were two small canes; they resembled hooked sais before Thieves in Time, where they were instead bamboo canes that could connect into one longer cane. He used the Spire Jump to sneak into heavily fortified castles in Japan. He was also responsible for the creation of the Leaping Dragon technique, allowing him to jump far distances from a ninja spire point. The Leaping Dragon was not recorded in the Thievius Raccoonus. He also invented sushi, with his first serving coming from his dying best friend and fellow ninja, who was a shark.
- Henriette Cooper – A female ancestor of Sly who sailed the seas circa 1616 AD and stole from other pirates. Originally wielding a hooked dagger, she lost a hand and replaced it with a hook shaped like that of the trademark Cooper cane.
- "Tennessee Kid" Cooper – Sly's outlaw ancestor from the Wild Western United States circa 1884. He carried two six-shot revolvers with hooked handles before switching to a single revolver rifle with a hooked handle named "Ol' Blue" by 1884. "Tennessee Kid" also invented the Raccoon Rail Walk and Rail Slide. He used these to his advantage, due to the fact that there were many train rails all over the land. He also created the Crackshot technique exclusively for gunslinging, and it was not recorded in the Thievius Raccoonus.
- Thaddeus Winslow Cooper III – A Cooper from Victorian-era London, 1839 or 1893,[note 1] who was the most "gentlemanly" thief and a master of disguise. He had a cane similar to Sly's; the only difference is a red ruby-like gem at the end of its hook.
- Otto van Cooper – A presumably-European ancestor of Sly who was a genius mechanic and skilled fighter pilot, much like Penelope. Due to his physical ineptitude, he used his talent to pull off heists with his machines facilitating his thievery. He kept some of his technical blueprints in the Thievius Raccoonus. The propeller blades of his biplane were shaped like the trademark Cooper hook.
- Conner Cooper – Sly's father, who used the same cane that now belongs to Sly. Before being killed by the Fiendish Five, he pulled heists with Jim McSweeney and Dr. M as a team, and also created a laser slide technique. He is usually seen either from the neck down or as a silhouette throughout the series. He did not write the laser slide move in the Thievius Raccoonus; rather, Sly learned the move while in the Cooper Vault.
The Thievius Raccoonus is an ancient book in which every Cooper Clan member since ancient Egypt has recorded their thieving escapades, in addition to instructions on their various moves. It was created by Slytunkhamen Cooper and was then passed down through the family for generations, but was later stolen and divided among the Fiendish Five on the day Sly was to inherit it. After 10 years, Sly tracked down the criminals and recovered the book, afterwards recording his own adventures in it. After Sly left the life of a thief behind to strike up a relationship with Carmelita in Sly 3: Honor Among Thieves, the Thievius Raccoonus fell into the care of Bentley, who became the first non-Cooper in history to write in it.
The Thievius Raccoonus again fell victim to criminal scheming, with Cyrille Le Paradox erasing its contents one Cooper at a time. The gang traveled through time and eventually restored the book to its completeness. Bentley is the current keeper of the book.
The Cooper Vault was home to all of the members' treasure and the deceased's weapons.
Its only entrance was an indestructible door which could only be unlocked by the Cooper cane. In Sly 3, Dr. M unsuccessfully tried to steal the treasures by breaking open the vault using machine force and forging the Cooper cane. After many unsuccessful attempts, he grew paranoid and constructed a heavily guarded fort around it. After recruiting a team of specialist thieves, the Cooper Gang penetrated the defenses around the island and entered the vault.
Inside, Sly and Carmelita defeated Dr. M, and all the while, the walls in the vault were caving in, which ended up killing Dr. M. Another entrance to the vault was found by Bentley after Sly marked it with his cane and pouch. After the gang went their separate ways, Bentley and Penelope built a new entrance with upgraded security.
- The circumstances resulting in most of the Coopers' deaths are unknown.
- There were some cut audio files in the final release of Sly Cooper and the Thievius Raccoonus that contained information about three cut Thievius Raccoonus pages with master thief moves from cut Cooper Clan members — Caroline Cooper's Short Range Teleport Power, Okey O'Cooper's Bizarre Spacial Relocator and Della de La Coopeur's Special Clue Collection Technique.