Doctor Vatm was a preeminent Nezu astrophysicist, who discovered that the asteroids bombarding his colony in 2373 were artificial in origin. He communicated this finding to Voyager, but was cut off shortly after by atmospheric interference.

Vatm had learned of the Etanian Order and had been secretly gathering tactical information about their starships. He had also learned that one of the Nezu colonists was working for the Etanians, and so feared that he would be prevented from bringing his data to the authorities. Thus, he hid the information in a data storage device on the roof of the mag-lev carriage of the planet's orbital tether.

Lieutenant Tuvok and Neelix met Vatm on the surface, and they repaired the tether carriage in the hopes of reaching an altitude where Voyager could rescue them. However, en route Vatm died of lydroxide poisoning. It was found that Vatm's fellow scientist Sklar was responsible, being an Etanian collaborator who sought to keep Vatm from helping the Nezu fight the Etanians. Tuvok and Neelix were able to recover Vatm's data, allowing Voyager to defeat an approaching Etanian starship. (VOY: "Rise")

Vatm was played by Tom Towles.