R. Roland

"Something happened. I don't know what. I... it was like a shockwave. I... it passed through the entire base."

- R. Roland to the Marine, talking about the demon invasion

R. Roland was a maintenance worker assigned to Mars City. He was one of the few UAC personnel to survive the initial demon invasion, as well as being the first survivor the Marine encounters.

History
When the player exits the Mars City Underground after the initial events of the demon invasion in Doom 3, R. Roland calls out from a ventilation shaft. He lowers a maintenance ladder, allowing the player to climb to his position. Having witnessed the shockwave that ripped through the base on Mars, he is frightened, and with good reason - he also witnessed the base's personnel being transformed into zombies. He implores the player to find help. If the player persists in speaking to him, he will strongly affirm that he doesn't want to leave his position in the maintenance shaft, believing it to be the only safe place, and further urge the player to find help.

Fate
While his fate is unknown, there is a good chance he would have lived long enough to be rescued at the end of the game, assuming he did not leave his hiding spot. However, according to the intro to Resurrection of Evil, the only known survivor of the incident on Mars is the player, implying that everyone else was killed off-screen during the course of the game.