Bob Cooper was the very first Cooper to ever live (lived in 10,000 BC), and makes his appearance in Sly Cooper: Thieves in Time. Being the leader of his tribe, Bob Cooper used his theiving skills to gather and provide food for them. This often involed Bob stealing pterodactyl eggs. Bob invented the first ever Cooper Cane, which he used to help him steal the eggs more efficiently. Bob lived during the period of the Ice Age. It was during this period, that Bob made himself known as the greatest thief of the Ice Age.
In Sly Cooper: Thieves in Time, all of the pterodactyl eggs are stolen by Le Paradoxand The Grizz. This took away Bob's purpose of hunting the eggs and providing for his family and also took away his title as the greatest egg thief ever. This sent Bob into a depression, causing him to gain weight and became easy for The Grizz to imprison him and give his cane to Le Paradox.
After successfully apprehending Toothpick in the wild west, Sly and the gang accidentally transport to the Ice Age. They would then discover Bob's location and rescue him from The Grizz. After helping Bob get back into shape, he would then join the Cooper Gang and help them retrieve their temporal sprocket by climbing up Frostbite Peak.
Later on, the Cooper Gang would infiltrate The Grizz's Purple Paw Paint Factory and confront him. Ultimately, Murray would be the one to fight The Grizz, and successfully so, defeating him and putting an end to The Grizz's reign.