Holden was married to actress
Brenda Marshall from 1941 until their divorce (after many long separations) in 1971. They had two sons, Peter Westfield (born in 1944) and Scott Porter (born in 1946). He also adopted Virginia, his wife's daughter from her first marriage.
Holden had a busy social life; he was best man at the marriage of his friend
Ronald Reagan to
Nancy Davis in 1952. He maintained a home in
Switzerland and also spent much of his time working for
wildlife conservation as a managing partner in an animal preserve in
Africa. His
Mount Kenya Safari Club in
Nanyuki, Kenya, (founded 1959) became a mecca for the international
jet set.
He began a long relationship with actress
Stefanie Powers which sparked her interest in animal welfare. After his death, Powers set up the
William Holden Wildlife Foundation, of which she is president, at their Mount Kenya Game Ranch.
Throughout his lifetime, Holden had reported affairs with a number of Hollywood actresses, including
Audrey Hepburn,
Grace Kelly,
Capucine, and a "yearly rendezvous" with
Shelley Winters.