"Billy's Theme Song" is the song performed by storyboard artist Adam Muto that plays when Finn and Jake find the sword of their hero, Billy, in the episode "His Hero." It briefly catalogs several of Billy's adventures, including the times he slew the Fire Count, rescued Cotton Candy Princess, cast down the Lich, killed an Evil Ocean, and fought a Giant Bear. It is the last song of season one.
Who's the greatest warrior ever?
A hero of renown!
Who slayed an Evil Ocean
Who cast the Lich King down!
And that time the evil Fire Count
Captured a damsel fair.
Who saved her with such bravery
She offered him her hair?
Also... he fought a bear!