(Played by Simon Pegg)
Even in the alternate reality created in 2233, Montgomery "Scotty" Scott had still matured into a brilliant young engineer by 2258—so much so that he'd brazenly debated a Starfleet instructor on relativistic physics and how it pertained to subspace travel. The professor saw transporter beaming as limited to 100 miles, Scott theorized instead a limit of adjacent planets—but his unauthorized experiment to test it led to the loss of Admiral Archer's "prized beagle."
Scott was apparently "rewarded" for that act by being stationed at a small automated Starfleet outpost on ice-planet Delta Vega with only fellow engineer Keenser. Upon the unscheduled arrival of young James T. Kirk and the Spock of the "Prime" universe, as events caused by the Narada temporal incursion unfold, the elderly Vulcan informed Scotty that he will one day discover the theory of transwarp beaming—and showed him how to do it so that Kirk can get back to the Enterprise and the Nero crisis.
Once aboard the Enterprise, having joined Kirk in that historic first at-warp beam-in, Scott was appointed to fill the vacancy left by Chief Engineer Olson's death. Within hours he also accomplished another first—a beam-in of two disparate targets onto the same transporter pad—and saved the ship from the black hole devouring the Narada by ejecting and detonating the Enterprsie's warp core to create a titanic counter-push.