It's not that I don't play video games, I don't even like video games. Yet, several times a week I find myself watching Tech TV's video game review show X-Play. Why? Because I am absolutely entranced by Morgan Webb; I am enchanted by her. Oh, Morgan....

The Very Model of a Modern Major General
United Federation of Planets
Starfleet uses a naval-based rank system:
Fleet Admiral
Admiral
Commodore (in disuse by the 24th century)
Fleet Captain
Captain
Commander
Lieutenant Commander
Lieutenant
Lieutenant (junior grade)
Ensign
**********
Chief Petty Officer
Senior Chief Specialist
Crewman (various grades)

Romulan Star Empire
The Romulan Guard also uses a naval system, with a Roman twist:
Admiral
Commander
Sub-Commander
Centurion

The Tal Shiar (the KGB), by contrast, uses a military (army) system:
Colonel
Major

Klingon Empire
The Klingon Defense Forces use a hybrid naval/military system:
General
Brigadier
Captain
Commander
Lieutenant

Cardassian Union
In a lovely change of pace, the Cardassian military (no known formal name) uses a homemade system:
Legate
Gul
Glinn

Breen Confederacy
Those wacky and mysterious Breens also use a homemade system, of which we have only one example:
Thot