Major general
From Halopedia, the Halo wiki
Template:Rank Infobox Major General is a general-grade commissioned officer of the UNSC Marine Corps, UNSC Army, and UNSC Air Force, equal in rank to Rear Admiral (Upper Half) in the UNSC Navy.
Given that other officer ranks command the same unit groupings as their modern day U.S. counterparts, a Major General probably commands division sized units. This has yet to be observed in the Halo universe though. They may also serve as high-level staff officers at major commands.
In informal settings, Major Generals are typically referred to simply as "General".
A Major General may be also referred to as a "two-star General" to distinguish it from the other ranks of General; so named for the two star rank insignia worn on the uniform.