(Portrayed by Anthony Rapp)

Lt. Commander Paul Stamets is the U.S.S. Discovery’s science officer and chief engineer, and was the partner of the late Dr. Hugh Culber. Brilliant, awkward, outspoken and not keen to make friends, his expertise is astromycology, meaning he knows more than anyone about space mushrooms and the vegetative part of a fungus called mycelium. Stamets collaborated with Lt. Straal, conducting research to "get to the living heart of the universe, the veins and muscles that hold our galaxies together." However, the Federation co-opted their research at the start of the Klingon-Federation War in order to develop an organic-propulsion system. Stamets was assigned to the Discovery, while Staal was assigned to the U.S.S. Glenn in order to expedite their research. 

Captain Lorca of the Discovery saw in their research the possibility of jumping through space at unimaginable speeds. Though he professed to pushing Stamets and Staal so hard in order to defeat the Klingons, his ulterior motive was to return to the Terran Universe and overthrow Emperor Georgiou. Staal, believing he’d made progress, tested the drive, but died along with everyone else on the Glenn. Stamets forged on, impatiently working with Cadet Tilly. Eventually, they harnessed the spore drive, with Stamets plugging into it as an organic navigator. The drive worked, and Lorca took advantage of it, giving the Klingons a run for their money and getting closer to home.

However, the jumps took their toll on Stamets, leaving him catatonic, but functioning within the mycelial network. When the Discovery crossed into the Mirror Universe, Stamets and Mirror Stamets came face to face, and Stamets was able to say goodbye to Dr. Culber, who'd been killed by Ash Tyler. Tilly soon revived Stamets, who then helped destroy the I.S.S. Charon and guide the Discovery back to the Prime Universe. 

For his efforts, Stamets received the Starfleet Medal of Honor and a promotion to Lt. Commander. He also accepted the Starfleet Medal of Honor on Dr. Culber’s behalf.