He married Margaret McGuigan, a native of Parkersburg, on September 8, 1907, and the couple had six children: William Howard, Irene May, Thomas Peter, Faustine Ellen, and the twins, Donald and Ronald.
Portrayed as a "man of extreme wealth with country ways," Bill Lee maintained a vegetable garden, kept various farm animals at his stately Houston home on Montrose Boulevard, and enjoyed spoiling all of his children and grandchildren.
Bill Lee lived to be sixty-nine years old, and at the time of his death on October 28, 1936, brought on by bronchial pneumonia, he made his residence at 4218 Montrose Boulevard in Houston.
Purportedly, McCarthy, a close friend of Howard Hughes, inspired the character of Jett Rink found in Edna Ferber's best-selling novel Giant.
Another of Bill Lee's children, William Howard, married into Hollywood royalty not once but twice: first to actress Hedy Lamarr from December 1953 until the couple divorced in 1960; and then to Gene Tierney in 1960.