William Lowe Waller Jr. (born February 9, 1952) is an American judge who served on the Supreme Court of Mississippi from 1998 to 2019.

[6] The junior Waller graduated from Murrah High School and Mississippi State University in 1974, where he was a member of the Sigma Phi Epsilon fraternity.

Waller was elected to the Mississippi Supreme Court in November 1996, for a term beginning in January 1998.

He supported adoption by the Supreme Court of mediation rules for civil litigation and served as chairman of the Mississippi Public Defender Task Force from 2000 to 2005.

Waller and his wife, Charlotte, have three children and are members of First Baptist Church Jackson, where he has served as chairman of the deacons.