Theadora Van Runkle (March 27, 1928 in Pittsburgh, Pennsylvania – November 4, 2011 in Los Angeles, California) was an American costume designer. 
The first films she designed costumes for were Bonnie and Clyde (1967), The Thomas Crown Affair (1968) and The Arrangement (1969), all of which starred Faye Dunaway, for whom Van Runkle also designed the gown Dunaway wore to the 1968 Oscars, as well as Dunaway's complete off-screen wardrobe at the time.
Van Runkle was nominated for an Oscar for Bonnie and Clyde (1967), and has been nominated twice more, for The Godfather: Part II (1974) and Peggy Sue Got Married (1986). She designed the costumes for Troop Beverly Hills (1989).
She was the recipient of the Costume Designer Guild's Lifetime Achievement Award in 2002.