Dark Star (1974), produced and directed by John Carpenter.
A dispirited crew, all recognizable hairy college dorm-types, fly a failing spacecraft on a many-year mission to blow up unstable planets. They have a pet alien: a beach ball with feet and a wicked sense of humor. Their commander is dead but frozen and in emergencies they can talk to him with a microphone. He sort of answers.
This micro-budget science fiction comedy started as a student film project. I don't know if it's for everyone, but it became a cult favorite with the SF convention crowd. Carpenter also wrote the music and co-wrote the story with Dan O'Bannon, who acted in it, edited it and did the production design.
Some good "quotes" from many earlier SF films: 2001: A Space Odyssey (1968), Dr. Strangelove (1964), Star Trek, even Silent Running (1972).
O'Bannon said Alien (1979) was Dark Star made scary, and there are similarities:
Hunting the alien through the dark compartments (and into the ventilator shafts!)
The "Mother" computer voice and her control room.
The "knife trick" from Aliens (1986)
I love how the slacker crew bursts into efficient switch-flipping during emergencies.
Another aspect, probably funnier now than then: arguing with the bomb, trying to prevent it from going off. Anyone who has struggled with the half-smart features of electronic appliances, especially when they start talking to each other, will know what that's about.
The image is very soft but that's how I remember the film itself.
A final bit of trivia I haven't seen mentioned elsewhere: the film features an instrumental number, "Where Twilight Falls on NGC 891". NGC 891 is known to amateur astronomers as the "Twilight Zone Galaxy" because a b&w image of it appeared in the opening credits of the 1950s TV show. I've seen the galaxy with my own eyes!
The DVD has a commentary track by a super-fan who has been watching it since he was age 8. He's very serious.