"Dark Frontier" is a feature-length episode of Star Trek: Voyager, the 15th and 16th episodes of the fifth season. This episode originally aired as a feature-length episode that was later broken up into two parts for reruns in syndication. Actress Susanna Thompson guest stars alongside the cast of this Star Trek television show as the Borg queen. The crew of a spacecraft trying to get back to Earth once again encounter a race of cybernetic organisms bent on Galactic domination. Ex-Borg character Seven of Nine (played by Jeri Ryan) struggles with her past as she rediscovers her humanity aboard the spacecraft.

The episode was written by Brannon Braga and Joe Menosky, with direction by Cliff Bole and Terry Windell. It aired on UPN on February 17, 1999.

"Dark Frontier" won an Emmy award for Outstanding Special Visual Effects for a Series.