"Borderland" is the fourth episode of the fourth season of the science fiction television series Star Trek: Enterprise. It originally aired on October 29, 2004, on UPN. The script was written by Ken LaZebnik, and was directed by David Livingston. The episode featured the first appearance of Star Trek: The Next Generation actor Brent Spiner in Enterprise. It also featured guest appearances by Bobbi Sue Luther and WWE wrestler Big Show.

The fourth season of the American science fiction television series Star Trek: Enterprise commenced airing on the UPN network in the United States on October 8, 2004 and concluded on May 13, 2005 after airing 22 episodes. Set in the 22nd century, the series follows the adventures of the first Starfleet starship Enterprise, registration NX-01. The fourth season saw changes made to the production team, with Manny Coto becoming the show runner. He had joined the team during the third season as a co-executive producer. Other changes included Star Trek novelists Judith and Garfield Reeves-Stevens being brought on board as writers.