Tash

From Memory Alpha, the free Star Trek reference.

Tash was an alien encountered by the USS Voyager in 2376. After he had been stranded far from home, he constructed a graviton catapult. As a reward to the crew for helping him to complete the catapult and successfully using it to return home, Tash sent recommendations for certain modifications to the device. Following the instructions for the modifications, Voyager used Tash's catapult to travel across thirty sectors in less than an hour, taking three years off their journey to Earth. (VOY: "The Voyager Conspiracy").

Tash was played by Albie Selznick. A blue version of the head prosthetic worn by Selznick as Tash was auctioned off in the It's A Wrap! sale and auction. This may suggest that Tash was intended to be a blue alien.