Robert Mitchum, 1949 © Ernest Bachrach.
Robert Mitchum and his wife Dorothy dance at a costume ball, c. late 1940s.
Ava Gardner and Robert Mitchum on the set of My Forbidden Past
Robert Mitchum in Rachel and the Stranger, 1948
Robert Mitchum was actually an accomplished saxophone player often whipping it out at parties or on movie sets and wowing people with his skills.
Happy Birthday Robert Mitchum!! | August 6, 1917 - July 1, 1997"You know what the average Robert Mitchum fan is? He’s full of warts and dandruff and he’s probably got a hernia too, but he sees me up there on the screen and he thinks if that bum can make it, I can be president."
The Night of the Hunter (1955)
I have never read anything saying he had a child with her.