Karen Thompson is a professional name used by the American voice actress Megan Hollingshead, who has built an extensive career in anime dubbing, animation, and video games since the 1990s. She adopted the pseudonym Karen Thompson for a number of her early roles in English-language adaptations of Japanese anime series.

Hollingshead began her voice acting career in New York City, where she became known for her work on some of the most prominent anime series of the era. She studied acting at the William Esper Studio and is a founding member of the Adirondack Theatre Festival. During the start of the seventh season of the Pokémon anime, she relocated from New York to Los Angeles to continue her voice acting career.

Under the name Karen Thompson, she voiced Lemmy Miyauchi in the anime series To Heart. She is also credited as Karen Thompson for her role as Mitsue in the series Journey to Hiroshima, and as Misaki Saiki in Ghost Talker's Daydream. In the series Fafner in the Azure, she provided the voice for the character Canon Memphis, another role performed under the Karen Thompson pseudonym.

Beyond these specific credits, Megan Hollingshead's voice acting career is notable for a wide range of high-profile roles performed under her own name or other aliases. She is widely recognized for her long-running performances as Nurse Joy and Cassidy in the Pokémon anime, and as Mai Valentine in Yu-Gi-Oh! Duel Monsters. Other significant roles in anime include Shizune in Naruto and Naruto Shippuden, Rangiku Matsumoto in Bleach, Re-l Mayer in Ergo Proxy, Villetta Nu in Code Geass, and Caster in Fate/stay night: Unlimited Blade Works. Her work has also extended into video games, where she is known for voicing Lenneth Valkyrie in Valkyrie Profile and its sequel, as well as roles in titles such as Eternal Sonata and the Fire Emblem series.

Throughout her career, she has collaborated frequently with various studios and directors involved in English dubs of anime, becoming a recurring voice in productions by companies like 4Kids Entertainment and later Bang Zoom! Entertainment. Her extensive filmography demonstrates a sustained and significant contribution to the field of English-language voice acting for anime.