Keir Gilchrist is a Canadian actor. He is most known for his role as teen Marshall Gregson on Showtime`s original series United States of Tara, written by Diablo Cody.

Keir Gilchrist was born and spent his early years in London, England. He and his family later relocated to Boston, Massachusetts, and then New York City before finally settling in Toronto, Canada.

He discovered his passion for acting at a young age, but it was his acting coach who persuaded him to take his passion to the next level and become a professional actor. Keir attended the Annex Children`s Theatre. He has a brother, Evan Gilchrist.