Billy

In his youth, Billy was very strong and brave, as well as kind and righteous (much like Finn). However, as Billy aged, he lost his sense of agency as his acts of heroism, in his eyes, failed to resolve anything in the grand scheme of the never-ending battle of good vs. evil. Over time, he focused less and less on heroic feats and adventures creating a literal void in his heart. However, after meeting Finn and Jake and becoming their friend, Billy 's void is filled, rekindling his love of being an adventurous hero.

Billy was a very tall humanoid with a long beard and long hair, making him resemble a caveman. In his youth, Billy's hair color was a bright red, but this grew white as the hero aged. His large and unusual hands contain six fingers including the thumb, though most humanoids in Ooo possess four-fingered hands. He had blue veins bulging out on the back of each hand, and his left shoulder bore a strange scar with stitches.

Billy wore no shirt or shoes and had brown pants. During his younger days, Billy possessed the Gauntlet of the Hero and used it extensively in combat. This weapon proved to be useful in aiding him during his battle with the Lich. In his dotage, Billy had a void in his chest where his heart would be until Finn's bold words fill it in "His Hero." He also appeared to have a magic sword called "Nothung" which he could summon by calling its name.