Lieutenant Spartan-B312 is a Spartan-III and a member of the UNSC Naval Special Warfare Command, with his most notable service being as "Noble 6" in Noble Team during the Fall of Reach. Known for going "lone wolf" in missions, he has an excellent history of single-handedly destroying entire rebel groups. In 2552, he was transferred to Noble Team where he replaced its former sixth member, Thom-293, who gave his life to destroy a Covenant Cruiser on an unnamed UNSC colony world (same operation where Kat-B320, Noble 2, lost her arm). Spartan-B312 is the player's character in Halo: Reach, and he is often referred to simply as "Six" or "Lieutenant" to give the player the feel that they are Noble Six. Look up "Noble Six" on Halo Nation for a more in-depth answer.