Stu is a Zigerion on the team of scammers attempting to steal Rick's recipe for concentrated dark matter in the episode M. Night Shaym-Aliens! He is the Zigerion who discovers Jerry's presence in the simulation and alerts Prince Nebulon. Like the rest of the Zigerions aboard the spacecraft, he is killed at the end of the episode when the "formula" they believe they scammed from Rick causes a massive explosion. He is voiced by Maurice LaMarche
While he only appears in the episode briefly, Stu seems more serious and professional than many of his colleagues. He doesn't whine or joke about Rick and Morty's nudity, instead remaining focused on his job.
Stu is also intelligent and efficient, being the first to realize a second human is in the simulation and quickly identifying him as Rick's son-in-law, Jerry Smith.
In the episode Close Rick-Counters of the Rick Kind, there was a picture of Stu on the wall of Rick's bedroom.