(written from a Production point of view)
Derek Magyar (born 18 July 1980; age 41) is the actor who played Commander Kelby, Enterprise NX-01's temporary chief engineer, and his mirror universe counterpart, in the fourth season of Star Trek: Enterprise.
Prior to his appearances on Enterprise, Magyar guest-starred on a 2003 episode of JAG along with Zoe McLellan, Jennifer Savidge, and Dean Stockwell. He then appeared in a 2004 episode of Boston Legal, the hit ABC series starring William Shatner and Rene Auberjonois. That episode also featured David Clennon, Michael Ensign, Louis Giambalvo, and Jack Shearer.
In 2005, Magyar appeared in a James L. Conway-directed episode of Charmed, co-starring Glenn Morshower. The following year, Magyar performed in his first feature film, playing the lead in the drama Boy Culture, along with Martin Squires
As suggested by the name, Derek Magyar is of Hungarian origin.