Peter Rasmussen Hallock (November 19, 1924-27 April 2014) was an American organist, choirmaster and liturgist. He was the founding director of the Compline Choir at St. Mark's Cathedral, Seattle, where he served from 1951 to 1991 as organist and choirmaster. He conducted the Compline Choir and its predecessor chant study group from 1956 to 2009.
Hallock pursued organ studies at the University of Washington, and also studied at the Royal School of Church Music. In 1986, with Carl Crosier, he founded Ionian Arts, a music publishing business.