Finn's mom

 is a character that first appeared in "The Lich." She appears after Finn and Jake are dragged through the Lich's portal, where she calls to Finn (who has a different face and a robotic arm) to come inside, and that it's very important he do so. She lives in a house similar to the farm house first seen in the episode "Thank You."

Appearance
She wears a purple dress and what appears to be a wedding band on her hand.