Martha Wainwright (born May 8, 1976) is a Canadian-American folk-pop singer. She is the sister of Rufus Wainwright and the daughter of Loudon Wainwright III and Kate McGarrigle.

Wainwright has received positive reviews for her performances. She appeared at the 2007 Bonnaroo and at Belladrum Tartan Heart Festival, Inverness-shire in August 2007. She recently duetted with Snow Patrol at the V Festival, and performed with her brother at the Hollywood Bowl in September 2007.

Wainwright married Brad Albetta in September 2007.

Annie Lennox joined forces with Martha and 22 other female artists to raise awareness of the transmission of HIV to unborn children in Africa. The single "Sing" was released on World Aids Day on 1 December 2007, when Lennox appeared at the Nelson Mandela 46664 concert in South Africa.

Her second full-length album, I Know You're Married But I Got Feelings Too, will be released in June 2008.http://blogs.livedaily.com/index.php/main/comments/1658/martha_wainwrights_sophomore_release_due_in_june.html

Singer-songwriter Martha Wainwright is the daughter of Loudon Wainwright III and Kate McGarrigle , and the sister of Rufus Wainwright . She has frequently appeared on recordings by her family members, and has released several independent EPs. Her full length self-titled debut was released in 2005 by Drowned In Sound. Most will have heard her without realising on the Snow Patrol single Set The Fire To The Third Bar from the album