Colonial Forces (Battlestar Galactica)
Original Series
There is no canonical list of rank insignia for the Colonial Forces in the original series. All Warriors below the rank of Commander wore the Colonial Warrior's Pin on both sides of the uniform tunic collar. This insignia was gold on the tan/brown service uniform, and silver on the dress blue uniform.
For those who do not recognize it, this is, in fact, the officer's insignia of the Military Intelligence branch of the United States Army.
In the original series, Commander Adama (Lorne Greene) also wore a different, larger, silver insignia, worn centered on the tunic, just below the collar.
No other readily identifiable rank insignia were worn in the original series.
New Series (2003)
A battlestar's crew, aside from the Marine Corps component present aboard the vessel, are Colonial Fleet personnel. As such, the crew falls into a common, hierarchical, military rank structure. This hierarchy is divided into two broad groups: Commissioned Officers, who exercise command oversight; and Enlisted personnel (to include Non-Commissioned Officers), who perform technical duties or exercise first-line supervisory authority. These two subdivisions are further separated into various ranks. These ranks each have distinctive insignia, which are worn on the collar of the Colonial Fleet uniform. The Colonial Fleet rank insignia are as follows:
Enlisted & Non-Commissioned Officers
File:Bg recruit.jpg Recruit File:Bg deckhand.jpg DeckHand
File:Bg specialist.jpg Specialist File:Bg petty officer.jpg Petty Officer
File:Bg chief petty officer.jpg Chief Petty Officer File:Bg master chief.jpg Master Chief Petty Officer
Commissioned Officers
File:Bg ensign.jpg Ensign File:Bg lieutenant jg.jpg Lieutenant (Junior Grade)
File:Bg lieutenant.jpg Lieutenant File:Bg captain.jpg Captain
File:Bg major.jpg Major File:Bg colonel.jpg Colonel
File:Bg commander.jpg Commander File:Bg admiral.jpg Admiral
While there are, presumably, a number of additional grades of flag rank, the television series hasn't provided any indication of the various admiral grades at the time of this writing.