Machen is a surname often but not always of Welsh origin (derived from the town Machen). Notable people with the surname include:
Alwyn Machen (1901–60), British trade union leaderArthur Machen (1863–1947), Welsh author and mystic, best known for his supernatural, fantasy and horror fictionBernie Machen (born 1944), American academic, President of the University of Utah (1999–2003) and of the University of Florida (from 2003)Eddie Machen (1932–72), American boxerHervey Machen (1916–94), U.S. Representative from Maryland 1965–69John Gresham Machen (1881–1937), American Presbyterian theologianRonald Machen (born before 1991), American lawyer, U..S. Attorney for the District of Columbia 2010–15Thomas Machen (c. 1541–1614), English merchant who was three times mayor of GloucesterWilliam H. Machen (1832–1911), Dutch painter and teacher who relocated to AmericaWillis Benson Machen (1810–93), U.S. Senator from Kentucky 1872–73