Karl Adolf Clark (20 October 1888, Georgetown, Ontario – 7 December 1966, Victoria, British Columbia) was a chemist and oil sand researcher.

He is best known for perfecting a process that uses hot water and reagents to separate bitumen from oil sands.

He began work at the Geological Survey of Canada in 1915, where he became interested in oil sands.

[2] Clark retired from the Department of Mining Engineering at the University of Alberta in 1954 but continued to provide advice to the developing oil sands industry.

In 1958 he signed a formal retainer with the Great Canadian Oil Sands consortium, which eventually became a major asset for Suncor.