Sentret made its debut in Pokémon Gold & Silver in 1999, alongside its evolution, Furret. It's currently unknown exactly who designed Sentret and Furret. Sentret's design is based off a few different real-world creatures - flying squirrels, rabbits, and meerkats. Furret is based off ferrets and meerkats.

May 6th, 1998 Possible Beta design		Early 1999 (?)		June 13th, 1999		August 17th, 1999		Final
	➜		➜		➜		➜
							➜
		➜			➜		➜

May 6th, 1998 Possible Beta design		Early 1999 (?)		June 13th, 1999		August 17th, 1999		Final
		➜			➜		➜
					➜		➜
		➜			➜		➜