Clement Lawrence Markert (April 11, 1917 – October 1, 1999) was an American biologist credited with the discovery of isozymes (different forms of enzymes that catalyze the same reaction).

He attended the University of Colorado, and in 1937, left college to fight in the Spanish Civil War—stowing away aboard a freighter to circumvent government travel restrictions.

[3] Markert's Ph.D. research, and subsequent postdoctoral work at Caltech, focused on the sexuality and other physiological and genetic aspects of Glomerella, a genus of pathogenic plant fungi.

In 1954, Markert became a victim of McCarthyism; he was suspended from teaching because he refused to testify before the House Un-American Activities Committee.

[5] Early in his career, Markert developed the concept of isozymes based on electrophoresis and histochemical staining of enzymes.