Lou Stein (April 22, 1922 – December 11, 2002) was an American jazz pianist.

Born in Philadelphia, Pennsylvania, Stein joined Ray McKinley's band in 1942. He played with Glenn Miller when the latter was stateside during World War II.

After the war he worked with Charlie Ventura (1946–47) and became a session musician. He performed with the Lawson-Haggart Band, Benny Goodman, Sarah Vaughan, the Sauter-Finegan Orchestra, Louie Bellson, Red Allen, Coleman Hawkins, and Lester Young, and recorded as a bandleader. In 1957 he had a U.S. Top 40 hit with "Almost Paradise", which peaked at No. 31 on the Billboard Hot 100. His cover version of "Got a Match" made the Cashbox Top 60 in 1958. He played with Joe Venuti from 1969 to 1972.