Muppets from Sesame Street skits aired around 1977-81. They were construction workers, and Sully was mute.

Biff would share his lunch with Sully, or vice-versa (as this memory is fuzzy and I can't remember), but they were friends and demonstrated co-operation and sharing to us wide-eyed viewers of PBS.

They were dropped, perhaps because of the fact that there was already one deaf person on the show, Linda or because Bert and Ernie carried stronger traits of dominance and submission and were even rumoured to be gay, and were much more popular. They could have been exhausted for ideas with them as well.

What Happens to Dead Muppets?