Memory Alpha
Memory Alpha
Multiple realities
(covers information from several alternate timelines)
Executive officer redirects here; for a business chief executive officer, please see CEO.
"Captain, as your exec, it's my duty to point out alternatives."
– Will Decker to James T. Kirk, 2270s (Star Trek: The Motion Picture)
"Commander, we don't have to like each other to work well together. As a matter of fact, I'd like you to continue to keep me on my toes."
"Some might define that as the role of a first officer."

Aboard a starship the first officer or executive officer (or XO) was the second-in-command, just below the captain.


In Starfleet, the position was usually held by an officer with the rank of commander or lieutenant commander, but exceptions do exist, such as with Sylvia Tilly in the 32nd century.

In Starfleet's early period of existence, the first officer would accompany the captain on landing parties, depending on the situation. By the 24th century, however, it was the first officer who usually led away teams while the captain remained on the ship.

In the 22nd and 23rd centuries, the first officer served as a department head first and the executive officer second (similar to the second officer and third officer) and only took command when the captain left the bridge, as such, there was no first officer's station as there would be in the 24th century, as the XO would alternate between the command chair and their station as a department head.

Noted functions of the first officer aboard a Federation starship were:

Aboard a Klingon warship, the first officer served the Captain, but stood for the crew. They also reviewed and kept the ship's record of battle. (DS9: "Soldiers of the Empire")

Noted first officers[]

22nd century first officers[]

23rd century first officers[]

24th century first officers[]

25th century first officers[]

29th century first officers[]

32nd century first officers[]

Alternate reality[]

Mirror universe[]

List of first officers[]


  • Lieutenant Commander Data
    • USS Enterprise-D (2369)


A deleted scene from Star Trek Nemesis introduced Commander Martin Madden as the new first officer of the USS Enterprise-E

Klingon Empire[]

  • Commander Kurn
    • USS Enterprise-D (2366, part of the Officer Exchange Program)


Mirror universe[]

Alternate timelines[]

  • Lieutenant Sato
    • Enterprise NX-01 (2165)
  • Commander Thelin
    • USS Enterprise (2269)
  • Commander Worf
    • USS Enterprise-D (2367 – 2370)



  • Commander Worf
    • USS Enterprise-E (2380)

External link[]