William Harper (born October 10, 1949) is a Chicago photographer and composer.

His photography is concerned with natural form and line and his music is theatrical, technology-based work sourced from liturgical and folk traditions.

Harper first earned critical acclaim for his work defining a Chicago style of new music theater and opera as the creator and producer of many full-length original works for the American Ritual Theater Company (ARTCO).

Concurrent with these projects, and subsequently, Harper's opera, music theater, dance, orchestra, chorus, and electro-acoustic works have been commissioned and performed by companies including The Minnesota Opera Company, The New Music Theater Ensemble of Minneapolis, INTAR Hispanic American Cultural Center, The Goodman Theater, Hartford Stage and The Music Theatre Group.

Harper's recently completed Unquiet Myths, a suite of electro-acoustic pieces was commissioned by The Ellen Sinopoli Dance Company for Spill Out!, which premiered in 2006 and is scheduled to begin a national tour this year.