Campbell is an alumna of Amsterdam's Boom Chicago, Northwestern University's The Mee-Ow Show, i.O., i.O. West, and Los Angeles' The Groundlings Sunday Company. Heather performs in and writes for The Midnight Show, a monthly Sketch showcase at the Upright Citizens Brigade Theater, UCB's Last Day of School, and is a performer on the CW's Whose Line Is It Anyway. Campbell was also a Writer on Cartoon Network's Incredible Crew. From 2013, she began writing for Adult Swim's The Eric Andre Show. She also currently writes for FOX's Animation Domination, and is a voice talent behind various short clips on Fox's Animation Domination High-Definition (ADHD) airing on Saturday nights. She has appeared on Comedy Central's @midnight four times.