Lieutenant Commander

Lieutenant commander is a commissioned officer rank in many naval services and space forces, most notably the Federation Starfleet.
== Standing ==
A lieutenant commander is a mid-level line officer rank, a grade higher than a lieutenant and a grade below commander in most rank structures, although some organizations may differ or omit this rank. The lieutenant commander rank is roughly equivalent with the authority of a major of military forces.
In the Romulan Republic Navy, the rank of subcommander (Romulan language erei'riov) is roughly equivalent to a Starfleet lieutenant commander, although Romulan subcommanders are often first officers and fill other positions with standings approximate of Starfleet commanders.
In the Cardassian language, dalin is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to a lieutenant commander.
A lieutenant commander in Starfleet may be assigned as a department head or senior staff member of a larger command such as a capital ship or starbase. A lieutenant commander could also serve as the commanding officer of a smaller starship or the first officer of a mid-size vessel. On larger vessels, a lieutenant commander could also fill a role as second officer or third officer.