Tonight I was watching Charlton Heston in the 1971 sci fi piece The Omega Man. A few minutes into the film the thought came to mind that Clint Eastwood could have played the lead in that movie. And that got me thinking that it's surprising Heston and Eastwood never did a film together. Given the kind of films both men did, especially westerns, and the tough guy characters they generally played, it's odd no one cooked up a project involving the two of them. Eastwood and Heston were friends, and reportedly talked about remaking Sam Peckinpah's Ride the High Country in the late '80s.
One genre that the two didn't share was science fiction. Other than a bit part early in his career Eastwood had no involvement in the genre. The closest he got after becoming famous was 2000's Space Cowboys. Compare this with Heston, who in the course of 5 years appeared in the first two Planet of the Apes movies, The Omega Man, and Soylent Green. It would be interesting to know if Eastwood was offered sci fi movies, but rejected them, or if he just wasn't considered for such films. The latter seems rather unlikely.