Randy McIlvain was a Starfleet officer in the 24th century.
In 2370, he was listed as a Science Ops officer on the dedication plaque of the USS Defiant on stardate 47538.5. (DS9: "The Die is Cast", dedication plaque)
In 2375, McIlvain was credited on a plaque as part of the R&D crew of the newly-constructed USS Sao Paulo. (DS9: "The Dogs of War" set artwork)