Spot

Spot is a pig that lives inside Oscar's trash can.

He appeared on Sesame Street in episode 2073, where he was played by a live pig.

Spot later became an unseen character for several years. Although not featured on screen, in episode 3782 Spot was said to be lamenting the absence of fellow-pet Slimey (who went to the moon); and he was heard using a jackhammer to help get Curly Bear to take her nap in episode 4078.

Spot finally re-appeared on camera over 20 years later (this time as a Muppet), appearing in episode 4178 where he received a mud bath from Mike Rowe.