Charles Swinnerton Heap (10 April 1847 - 11 June 1900) was an English organist, pianist, composer and conductor.
Heap was born in Birmingham in 1847 and educated at the town's King Edward VI School, where he studied the organ under Walter Brooks. At the age of 11 he performed as a boy soprano at the 1858 Birmingham Festival, the first conducted by . In 1862 he went to study under Dr. Edwin George Monk at York Minster. In 1865 he won the Mendelssohn Scholarship for young composers.
He then studied at the Leipzig Conservatoire, and then St John's College, Cambridge where he was awarded Mus Bac. in 1871 and Mus.D in 1872.
In 1884 he was appointed Examiner for Music Degrees at his alma mater, Cambridge University. He later taught at the Royal College of Music where one of his notable pupils was organist Herbert Sanders.
Heap was a the most important early patron of Edward Elgar, commissioning his work King Olaf, an important breakthrough in his career. Elgar later wrote that without Heap he would have "remained in outer darkness", and dedicated his Organ Sonata and the oratorio The Light of Life to him.
After Heap's death the composer Havergal Brian wrote to the secretary of the Royal Philharmonic Society, comparing Heap favourably to the better-known Frederic Cowen and Alexander Mackenzie: "What was the old Phil doing to miss such a genius? Cowen, Mackenzie and Co. weren't within a thousand miles of Heap – who died unknown outside the Midlands."