Heidi Hynden Walch (born February 1, 1971) is an American actress, voice actress, writer and singer who performed the voice of Harley Quinn in the 2014 animated film Batman: Assault on Arkham. She is best known for voicing Penny Sanchez in ChalkZone, Princess Bubblegum in Adventure Time, Starfire in Teen Titans and Teen Titans Go!, and Viridi in Kid Icarus: Uprising.
Walch who portrayed the character Ace in the shows Justice League and Justice League Unlimited which were part of the DCAU (DC Animated Universe) and was one of a number of actors who returned from the DCAU for the Arkhamverse such as Kevin Conroy, Mark Hamill, Arleen Sorkin, Tara Strong, Loren Lester, Robert Costanzo, Corey Burton, Khary Payton, CCH Pounder, Peter MacNicol, Michael Rosenbaum and Adrienne Barbeau who all returned in the Arkham games, although some, like herself, in different roles. However, Batman: Assault on Arkham was not her first instance voicing Harley Quinn as she had previously provided the voice for the character in The Batman 2004 animated series.