Mushroom-headed character of the Mario games

TOAD

This loyal sidekick often helps Princess Peach and wears a spotted cap, though he’s not a plumber like Mario.

This clue refers to Toad, the loyal mushroom-like companion in Nintendo’s Super Mario games. The "mushroom-headed" part describes his round, white-spotted cap, which resembles a toadstool—a playful nod to his name. He’s been a sidekick to Mario since the early games, often helping players with hints or power-ups. The clue keeps it simple by focusing on his most recognizable trait.