William L. McMillan (January 13, 1936 – August 30, 1984) was an American physicist noted for his research of condensed matter physics. ^{[1] [2] [3]} McMillan was a member of the National Academy of Sciences, professor of physics at University of Illinois, Urbana-Champaign.^[2][3] He was also a member of the American Academy of Arts and Sciences^[3] McMillan received the 1978 Fritz London Memorial Prize for his work in superconductors.^[3] The National Academies Press called him "the ablest condensed matter physicist of his generation".^[2] The University of Illinois established an award in his name: The William L. McMillan Award.^[4]

The electron-phonon coupling in superconductors is described by the McMillan parameter.

• 1936 born in Little Rock, Arkansas^[3]
• 1958: BS, University of Arkansas (Electrical Engineering)^[3]
• 1959: MS, University of Arkansas (Physics)^[3]
• 1964: PhD, University of Illinois, Urbana-Champaign^[3]
• 1964–1972: Bell Laboratories, Member, Technical Staff^[3]
• 1972–1984: University of Illinois, Urbana-Champaign, Professor of Physics^[3]
• 1978 Fritz London Memorial Prize for his work on superconductors
• 1982: elected to National Academy of Sciences^[3]
• 1983: elected to the American Academy of Arts and Sciences in 1983^[1]
• 1984: Died of an accident at age 48