Taught in the Chicago public schools system.
His first movie was The Package (1989), starring Gene Hackman and directed by Andrew Davis. It was filmed in Lennix's hometown of Chicago, where Davis (also a Chicago native) films most of his movies.
He went to school with David Schwimmer of Friends (1994).
He is the youngest of four children.
He was awarded the 1988 Joseph Jefferson Award for Actor in a Principal Role in a Musical or Revue for "Ma Rainey's Black Bottom" at the Pegasus Players Theatre in Chicago, Illinois.
He was awarded the 1989 Joseph Jefferson Award Citation for Actor in a Principal Role in a Play for "Caught in the Act" at the Lifeline Theatre in Chicago, Illinois.
He was awarded the 1997 Joseph Jefferson Award for Actor in a Principal Role in a Play for "Ma Rainey's Black Bottom" at the Goodman Theatre in Chicago, Illinois.
He graduated from Northwestern University in Chicago, Illinois.
Son of the late Harry Joseph Lennix II and Lillian C. Lennix of Chicago, Illinois.
He is the trustee of the Robey Theater Company in Los Angeles, California. [June 2009]
Has played husband to Valarie Pettiford, in the movie "Stomp the Yard" and the TV series "The Blacklist".
Attended Northwestern University with Stephen Colbert.
Stephen Colbert, on The Late Show in Aug 2016 with guest Larry Wilmore, recounted their post-White House Correspondents' Dinner speech experiences having to mingle with the people they had just skewered - many of whom apparently could not take a joke. Colbert recalled after his 2006 speech during which he had famously and mercilessly skewered then President George W. Bush, said actor Harry J. Lennix - the talented, very dignified actor and classmate of his from Northwestern University, came up to the dais to compliment him. Colbert remembered telling Lennix that he didn't think anyone liked him. "Lennix leans back," Colbert recalled, "and with his deep voice goes, 'Fuck these people. That was good'.".
Is a member of Omega Psi Phi Fraternity.