UNSC rank structure

The rank structure of the United Nations Space Command's mainline branches of service (the Navy, the Marine Corps, the Army, and the Air Force) is largely derived from the system employed by the 21st century United States military. Spartan Operations is an exception to this as its members lack conventional ranks.

Warrant officer
A warrant officer is a military officer in the armed forces ranking above a non-commissioned officer (NCO) but below a commissioned officer. Warrant officers are typically promoted based on their expertise in a certain field or job, and are considered experts in their area. The warrant officer ranks are as follows: Warrant Officer 1, Chief Warrant Officer 2, Chief Warrant Officer 3, Chief Warrant Officer 4, and Chief Warrant Officer 5.

Trivia
The Halo Encyclopedia erroneously describes the structure and insignia of the UNSC's ranking system as being identical to those used in Halo multiplayer, Halo 3 in the original printing and Halo: Reach in the 2011 edition.