(written from a Production point of view)
Scott Sterling Hill is the actor who appeared as a regular background performer on the last three seasons of Star Trek: Enterprise, most notably as relief helmsman Ensign Hutchison. He also portrayed a number of other background parts and was the first ever to reveal Xindi torso. Hill received no credit for his appearances.
Hill appeared in behind the scenes footage of the episode "Future Tense" on the ENT Season 2 DVD special "Shooting Future Tense".
Outside Star Trek, Hill portrayed a subway person in the 1990 independent film Underground, which also featured TNG guest actor Clement von Franckenstein, and performed in several stage plays such as Zipper in Sleeping Beauty (1999). 
More recently he had featured parts in Ron Howard's thriller Angels & Demons (2009, with Jon Donahue and Yuri Elvin), in which he played a monk, and in episodes of Desperate Housewives (2009, starring Teri Hatcher) and The Mentalist (2011).
Star Trek appearances
Appearances as Hutchison
(This list is currently incomplete.)