10 Best Family Guy Characters Only In One Episode

When Peter and the gang learn that a shipment of Mercedes sports cars was lost overboard on a cargo ship, they set out to see to try their luck at finding one for themselves. In doing so, they meet Billy Finn, a seemingly well-meaning talking dolphin who tries to locate the cars for them, but finds only a single hood ornament. Naturally, Peter takes to this just as fondly, just as he utters those famous last words: "If there's ever anything I can do for you..."

That same day, Billy shows up on his doorstep to take Peter up on his offer, and immediately takes advantage of the Griffins' hospitality. Sarcastic and unapologetically rude, Billy continues to guilt-trip the family into thinking they owe him, resulting in him staying at their house for way longer than he was invited for.

Eventually, it's revealed that he is on dry land because his wife kicked him out, so the gang scuba dives down to the bottom of the ocean in order to reunite the couple and get Billy back where he belongs.

With wonderfully dry voice acting by comedian Ricky Gervais, this character is absolutely the most impactful of Family Guy's one-time big hitters. Though his story is wrapped up nicely, Billy has since appeared in the background of some episodes, so it wouldn't be a stretch to say that bringing him back for another major role is a very real possibility.