Robert received a Best Supporting Actor nomination for his role in Jackie Brown at the 1997 Academy Awards. This was his first role in a major film since 1969's Medium Cool.
Robert told the New York Times in 1972 that he was not married to Marlene, the mother of his son Robert.
Robert's wife, June Provenzano, is the mother of his three daughters Elizabeth, Kathrine and Maeghen.
In 1967 Robert made his feature debut playing Private Williams in John Huston's Reflections in a Golden Eye in which there is a scene where Robert is riding a horse naked. The scene raised many eyebrows at the time.
One of Robert's companions was Dani Janssen, widow of actor David Janssen.
Robert's mother, Grace Dorothy Foster, divorced his father in 1949 and committed suicide in 1966.
Robert's father, Robert Wallace Foster, worked as elephant trainer with Ringling Bros. before working as an executive for a baking supply company.
Robert's daughter, Kare, played his niece in the movie Hollywood Harry (1985).
Robert's children are:
Robert Foster (born c. 1965).
Elizabeth Foster (born in 1967).
Kate Forster (born October 1969).
Maeghen Foster (born in 1972).
When things got financially very bad for Robert, a Spanish actor made three porn movies using his name and no one knew the difference.
Robert's daughter is actress Kate Forster.
Robert provides the voice for Midnight Louie, a crime-fighting tomcat in Las Vegas in the books-on-tape world.
The role of Jake Nyman in American Perfekt (1997) was written especially for Robert by British director and close friend, Paul Chart.
Robert appeared with former NFL star/actor Fred Williamson in four different movies: Night Vision (1997), Original Gangstas (1996), South Beach (1992) and Vigilante (1983).
Robert tested for a part in the film True Romance (1993) but Christopher Walken eventually got the role.
Robert once worked as a door-to-door vacuum cleaner salesman.
Robert has been cast in the drama pilot 13 Graves for Fox's 2006 pilot season.
Robert: (on Quentin Tarantino) Let me just jump in there. A couple of tiny things about Quentin. Not only does he inspire real confidence from his actors, but, for instance, he uses music occasionally. In the scene, when Pam walks towards me, the first time I see her, unbeknownst to me, from the sound department came that tune, and that swelled everybody's feelings in the shooting process. He did that in the car playing the delphonics, and one thing I never saw anyone else do and which is the way it ought to be done, when you did a telephone conversation with another actor, that other actor was on the other end of the phone even if it was in the middle of the night, and we had to wake up Sam Jackson at 4 o'clock in the morning. This guy does all kinds of little things that makes the actor know that not only is he in their corner but he wants them to be great. It inspires tremendous confidence amongst all of the actors in the picture.
Robert: (when asked how he felt about the reviews for "Diamond Men" that said that his career is in a come-back and that it's the twilight of his career) Well, you know what? The actor still gets up in the morning, if he's still got something to work with, you go out there and you do it. Never quit! If...you're in a 12 step program? Well, I've got a 3 step program, it's easier to remember.
Step 3 is NEVER QUIT. You can win it in the late innings if you never quit.
Step 2 is deliver excellence right now. This is the only moment you've got to work with. So, if you're delivering excellence right now, that gives you the best shot of the best future you've got coming.
Step 1, you've got to have a good attitude in order to delivery Step 2. If you've got a bad attitude, you cannot deliver excellence. Step 1 is accept all things, it doesn't matter if you're not getting the good jobs anymore, Bob. Just accept it. It doesn't matter that you're not getting the Winnebago anymore. Put it behind you, just like that! Your shoulders relax, suddenly you're ready to deliver excellence now. If you're holding onto negative stuff from before, you cannot deliver excellence. So, accept all things. It doesn't matter if she doesn't love you anymore, Bob. Put it behind you.
Robert: (when asked what was the most fun he had on any of his movies, and who was it with) Oh....God, I made one little picture of my own, and it's called Hollywood Harry. This little picture was the most stimulating period of my life. So, in terms of having fun, that stands about above all others, because I made it, I always say "not much, but not junk." It's a spoof of detective movies, I've done a lot of detectives. After that, it would be Jackie Brown, cause this guy gave me a GREAT part, and I had perfect confidence in him as a director. Quentin.
Robert: (about Quentin Tarantino and his relationship with the cast) This guy is very smart, and he's great to his actors. He wants them to be great. He keeps the stuff fresh. When he gave me the script he knew I hadn't had a big part like this in twenty-five years and he said, "Here, read this, and don't put any pressure on yourself. Just prepare the way you normally prepare." And I said, "Oh, what a liberating thing." This guy is totally secure. He doesn't seem to be worried about anything. He's as good a guy as I have ever worked with. He screened movies once a week for his crew. One of them was American Perfekt (1997), a recent indie film I did. The last week of production he threatened to screen it for the crew and I said to him, "Listen, there's a tiny bit of 'adult content' in this, so I don't want to hear any catcalls. I don't know if it this is the right thing to screen." He got on the walkie-talkie and said "Hey, anybody who wants to see Forster naked come on in!"
Robert: (on his character in Jackie Brown) This is the great noir hero. If Humphrey Bogart or Robert Mitchum were around today, they'd be playing that role.