A function aboard a starship, a second officer assumed command of the ship when both the captain and first officer were unavailable. It was common for a second officer on a Starfleet vessel to hold the rank of commander or lieutenant commander. It was common for a second officer to be a department head aboard the ship first, since the role of second officer was considered a nominal position. He or she was rarely involved in the day to day command of the starship or starbase the way the captain or first officer was.

It was standard procedure for the second officer to accompany the away team. (TNG: "Time's Arrow")

When the Satarran agent using the alias of Keiran MacDuff commandeered the USS Enterprise-D in 2368, he altered the computer records so that the ship's rightful first officer, Commander William T. Riker, was listed as the second officer. (TNG: "Conundrum")

List of second officersEdit

• Commander Pavel Chekov
  • USS Enterprise-A
• Lieutenant Commander Data
  • USS Enterprise-D
  • USS Enterprise-E
• Lieutenant/Lieutenant Commander Jadzia Dax
  • USS Defiant
• Lieutenant Klag
  • IKS Pagh
• Rata
  • Bok's Marauder
• Lieutenant Commander Montgomery Scott
  • USS Enterprise
• Commander Hikaru Sulu
  • USS Enterprise-A
• Lieutenant Hikaru Sulu
  • ISS Enterprise
• Timothy's father
  • SS Vico
• Commander Charles Tucker III
  • Enterprise NX-01
• Lieutenant/Lieutenant Commander Tuvok
  • USS Voyager
• Lieutenant Commander Worf
  • USS Defiant
  • USS Sao Paulo
• Major Malcolm Reed
  • ISS Enterprise