Dimitri Rezinov is a Russian cosmonaut and crew member of Expedition 31 to the International Space Station, alongside NASA astronauts Howard "Froot Loops" Wolowitz (payload specialist) and Mike "Mass" Massimino. He appeared inside the Soyuz Soyuz capsule in a Sokol space suit and in the International Space Station; he has an easygoing demeanor preceding launch of their Soyuz rocket and finds humor in Howard. Amidst systems checks, Dimitri questions if the origin of Howard's nickname is because of his haircut. He is less accepting of the actual reason being that Wolowitz lives with his mom and she makes him Froot Loops cereal.
Natalya Simonova from the Bond movie Goldeneye, isn’t technically a cosmonaut, she’s a computer programmer at Severnaya, but hey, that’s close enough for us! She survives the massacre of her colleagues and the subsequent EMP attack on the facility. She then starts searching for the other survivor, Boris Grishenko, and meets James Bond along the way. Possibly the most clever Bond Girl in the entire film series, she is often shown thinking on her feet to stay ahead of the villains.
Ensign Pavel Andreievich Chekov was the ship's navigator on Star Trek TOS from Season 2 onwards. Chekov had a tendency to refer to Glorious Mother Russia and claim that any human advancement, be it technological or cultural, originated there. He also had terrible luck and frequently ran foul of whatever physical or psychological menace the ship was facing that week, mainly because Walter Koenig had an excellent capacity for screaming. Aside from that, he and Sulu were good friends and would frequently banter about the action. Chekov was, by far, the most junior of the regular bridge officers, but the writers justified his presence by having him act as the relief science officer whenever Spock was busy or incapacitated. In Star Trek III: The Search for Spock, in a nod to this, Chekov identifies himself as the "Acting Science Officer" of the Enterprise.
Lev Andropov from Armageddon is kooky as all hell, but he's still an incredibly competent cosmonaut, saving the lives of the crew on no less than three occasions. When he, A.J. and Bear are alone in the other Armadillo, he volunteers for a "spacewalk" to fix damage on the Armadillo's exterior as the only qualified astronaut available, even though he has no real experience with the Armadillo. He survives the destruction of the space station, of the shuttle, and a rock storm while repairing the Armadillo, the last of which was floating through zero gravity at the time. The only Russian on the team, and a deeply eccentric man never short of snark or a witty comment.
Cosmo from the MCU franchise was a Soviet space dog during the 1960s. She was launched into Earth's orbit by the Soviet space program as part of an experiment but was lost in space, arriving on Knowhere and at some point being mutated by cosmic rays. Now a telepath, she eventually comes to serve as the station's security chief. She appears in the first GoTG movie as part of the Collector's collection, with basically no involvement to the main plot of the movie or interaction with the main characters despite growling at Rocket, with her inclusion in the movie only serving as an Easter Egg for comic fans. In the GoTG Holiday Special, she has a speaking role, reveals her telekinetic powers, interacts directly with Rocket and is mentioned by the other Guardians. Vol. 3 gives her way more prominence by having her involved in several scenes on Knowhere, including the big finish of the film. She's also part of the new Guardians of the Galaxy team at the very end.