Mosko was a makeup artist on Star Trek: The Next Generation since at least the fourth season, although he did not receive credit until the seventh season. During that final season, he worked simultaneously on Star Trek: Deep Space Nine and continued with that series after TNG ended, but he did not receive credit for his work. He also worked on Star Trek: Voyager and didn't receive credit for the majority of his work on this series, either. He left the franchise following DS9's fourth season and VOY's second season; before he departed, however, he finally received makeup credit in three episodes near the end of VOY's second season: "Innocence" , "The Thaw" , and "Tuvix" .