Tim is Cleveland Brown's new neighbor on The Cleveland Show who just happens to be a bear.
On Family Guy, he made a cameo appearance in "Spies Reminiscent of Us", stating he didn't understand the recurring gag of Cleveland taking baths during crazy shenanigans.
Tim portrays Wicket, one of the Ewoks in It's A Trap!.
Tim is voiced by Seth MacFarlane.
Quagmire comments of Seth's handing of the voice of Tim off to others in "He's Bla-ack!".
Tim, along with a slew of other characters from The Cleveland Show, appears outside of the Griffin Home as a potential candidate for replacing Peter on Quagmire's father-daughter camping trip in "No Giggity, No Doubt".
See Tim on The Cleveland Show Wiki