First officer

A First officer (aka Executive officer, XO, and Number One) is the second-highest ranking officer aboard a starship or space station, usually a Commander or Lieutenant Commander. He or she takes command if the commanding officer is unable to. If the first officer is also unable to take command, the second officer is in charge.

First officers by name

 * Lieutenant George Samuel Kirk Snr. of the USS Enterprise (NCC-1701) (2243)
 * Commander William T. Riker of the USS Enterprise-D;
 * Commander Shundresh of the USS Enterprise (NCC-1701) (2245-2251)
 * Commander Christine Vale of the USS Titan

First officers by post

 * USS Enterprise (NCC-1701)
 * Lieutenant George Samuel Kirk Snr. (2243, KIA)
 * Commander Shundresh (2245-2251)
 * USS Titan: Commander Christine Vale

2243

 * Lieutenant George Samuel Kirk Snr. of the USS Enterprise (NCC-1701)

2345

 * Commander Shundresh of the USS Enterprise (NCC-1701)

2379

 * Commander Christine Vale of the USS Titan