Villains, or bosses, are the main antagonists in the Sly Cooper series.
Please see the respective article for more information about each villain.
Sly Cooper and the Thievius Raccoonus
- Fiendish Five
See: Fiendish Five
- Sir Raleigh; resided in the Welsh Triangle and used a storm machine to cause boat wrecks, which he looted. Stole a section of the Thievius Raccoonus.
- Muggshot; resided in Mesa City and forced the residents to vacate in order to build a casino. Stole a section of the Thievius Raccoonus.
- Mz. Ruby; resided in Haiti and raised the dead with plans to take over Mexico. Stole a section of the Thievius Raccoonus.
- Panda King; resided in China and forced innocent villages to pay a "protection fee" to keep him from sinking their village in snow with his fireworks. Stole a section of the Thievius Raccoonus.
- Clockwerk; resided in the Krakarov Volcano and was the leader of the Fiendish Five. Led the gang to murder Sly Cooper's parents. Stole a section of the Thievius Raccoonus.
Sly 2: Band of Thieves
- Klaww Gang
See: Klaww Gang
- Dimitri Lousteau; resided in Paris and was the owner of a Nightclub that was a front for a counterfeiting operation. Stole the Clockwerk Tail Feathers.
- Rajan; resided in India and wanted fame while he also produced a powerful Illegal Spice. Stole the Clockwerk Wings and Clockwerk Heart.
- The Contessa; resided in Prague and was the owner of a rehabilitation center where she hypnotized criminals into giving her the location of their riches. Stole the Clockwerk Eyes.
- Jean Bison; resided in Canada and was a gold miner from the 19th century who was frozen and then thawed out in modern times. Used his trains to transport spice. Stole the Clockwerk Lungs, Stomach and Clockwerk Talons.
- Arpeggio; resided on a self-built blimp and wanted to fly, but didn't have the body to do so. Stole the Clockwerk Brain and other integral parts.
- Neyla; was an INTERPOL agent that betrayed the Cooper Gang and Carmelita for fame. Was secretly in league with Arpeggio.
- Clock-La; a strange amalgam between the mind of Neyla and the body of Clockwerk. Neyla betrayed Arpeggio to become immortal using the Clockwerk frame.
Sly 3: Honor Among Thieves
- Don Octavio; resided in Venice and wanted to punish all those who disrespected his music of choice, Opera.
- Mask of Dark Earth; was buried in the Australian Outback for hundred of years, but was released by overzealous opal-miners.
- Black Baron; resided in Kinderdijk, Holland and was the reigning champion in his own competition. Was actually Penelope disguising herself in order to enter flight competitions, which barred her young age.
- General Tsao; resided in China and was holding Jing King, the Panda King's daughter, hostage in attempt to get her to marry him, joining two powerful families and allowing him more powerful dark magic.
- Captain LeFwee; resided in Blood Bath Bay and leaded a life of piracy. Kidnapped Penelope in attempt to get her to marry him.
- Dr. M; was set up on Kaine Island, and was paranoid about what riches may be held in his Conner Cooper's, his old partner, family vault.
Sly Cooper: Thieves in Time
- Le Paradox's gang
See: Le Paradox's gang
- El Jefe; a ruthless Cuban military strategist that collected countries to sell to the highest bidder in exchange for royal status in Feudal Japan.
- Toothpick; an Eastern-European mob boss with a fondness for both gold robberies and cowboy movies. Wanted to steal gold from the past and move it into the future, which would make himself a billionaire.
- Grizz; a street punk who formerly had celebrity status in the art world, but lost it after his art lost freshness, and attempted to gain riches by hiding art in the past, which he wanted to unearth in the future.
- The Black Knight; a giant metal suit that Penelope takes control of. Worked with Le Paradox to get a jump-start in the weapons trade after betraying the Cooper Gang.
- Ms. Decibel; a musician who was ridiculed as child for her inability to play the trumpet, and used her new-found ability to hypnotize to help her in a life of crime. Hypnotized forgers into turning Le Paradox into a royal in the future in exchange for his love.
- Cyrille Le Paradox; a French art collector who attempted to get revenge on the Cooper family for the embarrassment Conner Cooper caused his father.
Sly Cooper: Thieves in Time
- A male elephant holding what appears to be a set of scrolls, books and other such objects. He was meant to be the boss of Ancient Arabia, and was most likely hired to fabricate Le Paradox's documents in that era. He was eventually merged with another boss character to create Ms. Decibel. Aspects of this character remain in the final game, such as elephant statues holding books in their trunks acting as fountains.
- A female monitor lizard that appears to be some sort of wealthy aristocrat. It isn't known what role she would've had as of yet, other than that she was supposed to be a boss. Her character was eventually merged with another character to make Ms. Decibel.
- A mole with a large drill-like contraption strapped to his back. He was the original boss of Medieval England, as Penelope was not included in the original boss lineup.
- A spider character from Paul Sullivan's website containing his goons and castle which never had a chance to be featured on account of lacking black magic in the fourth game.