An alien supervisor who arrives in 2375 to close a subspace sinkhole that has swallowed many ships, giving Voyager only a short time to recover its stranded crew.
Supervisor Yost appears in the fifth-season Voyager episode Gravity, played by Paul S. Eckstein. He commands a vessel sent by his people to collapse a gravitational sinkhole that has claimed a number of their ships, pulling them into a pocket of subspace containing a desert planet.
Voyager is searching the area for a missing shuttle carrying Tuvok, Tom Paris and the Doctor when Yost makes contact. He is courteous but immovable: the danger to shipping is too great to delay, and the sinkhole will be sealed on schedule.
He grants Captain Janeway a brief extension, which forces the crew to work against the clock. Because time passes far faster inside the anomaly, the deadline turns hours on Voyager into months for the castaways, who are beamed out moments before the opening closes.