The Trap Door

Nasty Beasty (2x13)

Air date: Jul 14, 1990

It is the middle of winter and Berk has to mend the Thing Upstairs's heater. Rogg comes up from the trap door with a green fuzzy thing stuck to him. This is the last time that the Thing Upstairs is heard, with the following episode being the last time he is actually referred to.