Marcia Llyneth Griffiths (born 23 November 1949, Kingston, Jamaica) is a successful female singer, also called the "Queen of Reggae". One reviewer described her noting "she is known primarily for her strong, smooth-as-mousse love songs and captivating live performances".

Griffiths started her career in 1964. From 1970 to 1974 she worked together with Bob Andy in the group Bob and Marcia, on the Harry J label. Between 1974 and 1981 she was a member of the I Threes, a background group, which supported Bob Marley & the Wailers.

Her song "Electric Boogie", released in 1976 and re-released in 1989, made the Electric Slide, a line dance, an international dance craze. It reached number 51 on the US Billboard Hot 100 making it her most successful single. It remains the highest-selling single by a female Reggae singer of all time.