(written from a Production point of view)
Matthew McGregor (born 15 July 1984; age 32) appeared as a background Starfleet cadet in J.J. Abrams' Star Trek. He was part of the group of actors who worked in a big crowd scene at the Cal State Northridge campus which stood in for the Starfleet Academy. McGregor filmed his scenes in December 2007 and was called back for reshoots in March 2008. 
McGregor was born in Levittown, New York, and is the nephew of hair stylist Paul McGregor. He moved to California in 2007 and worked as salesperson for several companies including S&S Tuxedo's and K-Mart. He then worked behind the scenes as a stage crewmember on the show Saturday Night Live and as a page for NBC. Prior to his move to California he worked as assistant set dresser for the horror thriller Dark Water (2005) and the television series Rescue Me and as a craft service member for the fantasy comedy film Enchanted (2007).
More recently, McGregor was an extra on the reality show How to Look Good Naked (2008). He also served for one week as a production assistant on the science fiction remake The Day the Earth Stood Still (2008, with Roger R. Cross and Geoff Meed) and as an office production assistant on the television series 90210 (2008).