Dr. Richard Daystrom is a character from the fictional Star Trek universe. He appears in the Star Trek: The Original Series episode The Ultimate Computer.

Daystrom is a renowned computer engineer of the 23rd century, who pioneered the duotronic computer systems in service on all Starfleet vessels. Daystrom's newest technology was the revolutionary multitronic M5 Computer System which could simulate human thinking. If successful, the computer could replace the entire living crew of a starship. M5 was the fifth design; the other four didn't perform very well, but M5 was the "ultimate" version and was ready for trial runs.

The secret of M5's capabilities was that it was patterned after Daystrom's own mind. Unfortunately, Dr. Daystrom suffered from an undiagnosed mental psychosis and became very delusional under the pressure. The M5, being an electronic copy of his own mind, also became erratic. During simulated war games, M5 made deadly attacks against other Federation ships, and had to be shut down.