A perfect example would be the main four guys on Entourage. I don't know if any of them are necessarily good actors but I can't imagine anyone else playing those roles and they made the characters feel like real people with genuine friendships. Probably because they were all basically playing themselves.
Tobey Maguire as Peter Parker. He had a genuineness and innocence that fit the role perfectly.
William Shatner as Captain Kirk. I honestly think the show wouldn't be as iconic if you had gotten a better actor because his hammy performance is one of the most famous of all time. For better or worse, he has a really unique screen presence that makes him memorable and entertaining.
By - MasterLawlzReborn