First Officer

Executive officer, second-in-command, just below the captain
Attending important meetings and briefings with the captain
Take command of the vessel in the event of the captain's absence
To point out any actions that may be mistakes by a commanding officer
Preparing and issuing duty rosters

T'Pol
Una Chin-Riley
Spock
William T. Riker
Kira Nerys
Aaron Cavit
Chakotay
Jack Ransom
Adreek-Hu
Tysess
Raffaela Musiker
Rayner