Marnie McPhail Diamond is a well-known American-born Canadian actress and musician. She is famous for her roles as Maria Wong in Braceface, Annie Edison in The Edison Twins, and Peaches in JoJo's Circus.

McPhail was born and raised in Columbus, Ohio, U.S. She later moved to Toronto, Ontario, where she attended the Etobicoke School of the Arts. When she was 14 years old, she got her first major role as Annie Edison in the children's television series The Edison Twins (1982).

On the set of Scared Silent (2002), McPhail met her husband, Reed Diamond, and they have been happily married since 2004. Both McPhail and her husband are members of the rock band "Chuck Valiant," with McPhail as the lead singer and Diamond playing the guitar.