100th Window is the fourth studio album by English electronic music group Massive Attack, released on 10 February 2003 by Virgin Records. The album was mainly produced by lead member Robert Del Naja, as the group's producer Andrew Vowles departed shortly after the release of their previous album Mezzanine (1998), and Grant Marshall opted out of the production of the album. 100th Window features vocals from regular guest Horace Andy, as well as newcomers Sinéad O'Connor and Damon Albarn. Stylistically, it is the first album by the group to make no use of existing samples, and contains none of the hip hop or jazz fusion styles that the group were initially known for.

Massive Attack are an English trip hop collective formed in 1988 in Bristol by Robert "3D" Del Naja, Adrian "Tricky" Thaws, Andrew "Mushroom" Vowles and Grant "Daddy G" Marshall.