Phoenix Logs/Leaders/Sergeant Johnson
From Halopedia, the Halo wiki
That's Sergeant MAJOR Johnson to you, chucklehead!
From the halls of Installation 04 to the shores of Harvest, Sergeant Johnson represented the UNSC with distinction and honor his entire life, and is remembered as a hero in death. However, in a twist of fate [and poor records—keeping], the UNSC Marine Corps accidentally assigned the life—challenged veteran to a position on board the long-lost Spirit of Fire. Even with the small handicap of being dead, Johnson isn't one to disobey a direct order from his beloved Corps and he sprung back to life ready to kick all butts that need kicking. The subsequent story of how he arrived at his new duty station is still classified, but trust us, it's a good one.
Sergeant Johnson favors a strong defense backed by heavy bipedal killing machines: Siege Turret Drop and Bunker Drop extend his fortifications, while EMP MAC Blast and Mech Overcharge give his combat walkers an upper hand in critical battles. But that's not all, the Corps has seen fit to issue Sergeant Johnson the Digging In Deep advanced power, letting him construct all structures on existing bases [excluding turrets] for free. Oh, and he can also get up close and personal with the Banished by leading from the front lines in the Green Machine, his personalized HRUNTING/YGGDRASIL MARK I[J] Armor Defense System.