Buzz Aldrin was the second man to walk on the moon.
In the Timeless Universe
In the original timeline, Neil Armstrong and Buzz Aldrin performed the Apollo 11 mission without any sabotage.
In the altered timeline, Armstrong and Aldrin's life was put in jeopardy when Garcia Flynn and Anthony Bruhl uploaded a modern computer virus onto NASA's equipment. The virus disrupted NASA's ability to communicate with the astronauts. Armstrong and Aldrin's life was eventually saved by the combined efforts of Rufus Carlin and Katherine Johnson.
Buzz Aldrin at Wikipedia