The 77th Marine Regiment was a UNSC Marine Corps infantry unit that fought against the Covenant Loyalists during the Second Battle of Mombasa, under the command of John-117. It is depicted in the "Believe" marketing campaign for Halo 3.
|Pawel Czernek||Major Pawel Czernek, who was active for 30 years in the UNSC from 2551 to 2581, was one of the few surviving combatants who fought in The Battle of New Mombasa, was interviewed in a documentary circa the turn of the 27th century at the Museum of Humanity. He related his role in the battle while examining a diorama of the battle - he manned an overturned Warthog's turret - and described the morale Master Chief engendered during the battle ("We knew Master Chief was in the fight. He gave us hope.") The elderly Major Czernek wears a prosthetic metal right leg; it is unclear where or when he suffered that traumatic injury.|
|T. B. Williams||T.B. Williams was a UNSC Marine present at the Battle of Earth. He employed a Sniper Rifle, and used it to kill a Jiralhanae Chieftain that was responsible for the deaths of more than 23 other Marines.|
|Ian Callahan||Ian Callahan was a Marine who was captured by two Kig-Yar during the Battle of New Mombasa, and was saved by an unknown Marine.|
|James Dessen||Corporal James Dessen was posthumously awarded the Red Legion of Honor medal for his extraordinary bravery during the Battle of New Mombasa.|
|Thomas P. Porter||Thomas P. Porter was a Scorpion driver during the Battle of New Mombasa.|
|Thomas Chang||Sergeant Thomas Chang was a veteran of numerous battles against the Covenant, and successfully completed the task of securing a forward HQ during the Battle of New Mombasa. He was killed during a Covenant air assault.|
|Jackson Law||Jackson Law was the sole survivor of a Warthog patrol during the Battle of New Mombasa. He sustained serious injuries when his Warthog was capsized by a Covenant plasma round.|
|Sian Wong||Sian Wong was a sniper that sustained severe burn injuries from a retaliatory Banshee strike.|
|Russel Tinnier||Russel Tinnier was a Marine assigned to destroy a strategic bridge.|
|Thomas C. Meyer||Thomas C. Meyer used his rocket launcher to destroy the bridge alongside Tinnier.|
|Emmanuel "Emmet" Lomax||Emmanuel Lomax encountered John-117 during the Battle of New Mombasa, after receiving a precious four-hour sleep in an abandoned building.|
|Caio Zanato||Caio Zanato was the sole survivor of his squad during the Battle of New Mombasa, promoted to the rank of Private First Class.|
|Niraj Shah||Lieutenant Niraj Shah was a sniper who participated on in the Battle of New Mombasa. He was seen fighting on a hill. He has severe plasma scarring on the right side of his face, likely by being grazed by a plasma round.|
- The regiment's number (77) is most likely a 7 reference.