Sir Galleth Cooper, also known as "Sir Galleth of the Knights of the Cooper Order", is Sly's ancestor from Medieval England. Sir Galleth was a courageous and charismatic knight with great thieving abilities.
In 1301 AD, Sir Galleth was imprisoned and had his cane taken away by the "Black Knight". He was imprisoned in a circus tent, which was suspected to have been done to entertain the king at the time. Sir Galleth says he was imprisoned for about a fortnight, which means two weeks. The Black Knight disrespected Sir Galleth, making fun of him and then taking over England and the castle. When Sly and the gang time travel to England, they learn of this and track down Sir Galleth. Sly would then eventually free and rescue Sir Galleth from his imprisonment.
After the Cooper Gang help Sir Galleth take his revenge and defeat the Black Knight, Sir Galleth has to face off against the Moat Monster, a three-headed dragon. However, the dragon ends up swallowing Sir Galleth, but only to be rescued by Carmelita Fox.
After retrieving his cane at the end of Sly Cooper: Thieves in Time on Le Paradox's blimp, Sir Galleth returned to England to form The Knights of the Cooper Order- a group who stole from the corrupt. Sir Galleth also pursued the entertainment industry, becoming a successful actor.