Tim is a Watchdog first seen in the episode "The Gift 2: The Giftening" as the first happy Watchdog.
He later reappears in "The Gift", which explains how he got the Gift in the first place: he was looking for the conference room, but got lost, and Wander and Sylvia gave him a gift, which made him happy.
Tim returns in "The Search for Captain Tim", where he is frequently mistaken for Captain Tim. Along with Hater, Ripov, Peepers, Wander and Sylvia, Tim is captured by the Arachnomorph Queen, but saved and freed by Captain Tim.
He looks identical to the other watchdogs.