What was the TV series about a man and big white balloon?

You are probably thinking about the NBC comedy-drama series ALF (1986-1990), which featured an extra-terrestrial named ALF (Alien Life Form) from the planet Melmac who crash-lands on Earth and moves in with the Tanner family. ALF is a sarcastic and often mischievous character, and the series follows his interactions with the Tanners and his attempts to adjust to life on Earth.

ALF is a puppet character who was voiced by actor Paul Fusco. The series was created by Tom Patchett and Paul Fusco, and it aired for four seasons on NBC.