Slaigh MacCooper, alternatively spelled Släi MacCooper, was a male member of the Cooper Clan during the Celtic Scotland era of the 15th Century.
The strongest of all of the Coopers, it is said he could break any lock with a single blow using his large stone cane. Slaigh was abnormally large for a Cooper, so he had to adapt by sticking close to the shadows by utilizing a "wall slide" maneuver. His immense strength allowed him to take things more by force than stealth. In the Cooper Vault, he protected his treasure by lifting enormous stone hammers onto a mechanism which showcased his thief ability of wall sneaking. He left behind his stone cane and an open forge possibly hinting he was also a blacksmith. He also left a wooden shield, and many wooden bowls with spoons on the floor.
- It's unknown how MacCooper was able to use the wall sneak, given his large size, though Murray, quite large himself, was able to perform the move in Sly 2: Band of Thieves, and in a few places in Sly 3: Honor Among Thieves.
- It is unknown what the true spelling of his name is. In Sly 3, it is spelled Slaigh, but in Sly Cooper and the Thievius Raccoonus, it is spelled Släi.
- Slaigh is the only major member of the Cooper Clan that isn't referenced at all during Sly Cooper: Thieves in Time.