Izzy
From Muppet Wiki
Izzy is Telly's cousin. He appeared in episode 4029 of Sesame Street.
Telly worries that Izzy won't like triangles, but it turns out that Izzy likes them so much that he bullies Telly and steals them.
Telly kindly asks Izzy for them back, but it doesn't work. Gordon asks Izzy how he would feel if he took his hat, which helps Izzy to reconsider.
Big Bird invites Telly and Izzy to play softball, an activity which won't endanger Telly's triangles.
