Serpent Tail has always taken on a job by the highest payer, although they do refuse those that they are uncomfortable with. Using both Earth Alliance and ZAFT equipment to complete their jobs, this mercenary group boasts a nearly perfect job completion record. It has no government whatsoever, operating primarily in teams. Their leader is Combat Coordinator Gai Murakumo, who pilots one of the three Orb Astray prototypes - the MBF-P03 Gundam Astray Blue Frame and its upgrades - and is considered by many to be the deadliest warrior in the Earth Sphere. Gai's team operates from either a captured Laurasia-class frigate or an unmarked civilian freighter, with his subordinates consisting of fellow pilot Elijah Kiel, the ship's captain and intelligence operative Reed Wheeler, explosives expert and tactician Loretta Adja, and client liaison Kazahana Adja.
Gai Murakumo is a Coordinator and leader of the mercenary group Serpent Tail. Before coming to Serpent Tail, he escaped from the Earth Alliance, breaking free of his mental conditioning. Although he is a skilled pilot and has no attachment to the machine he uses, he eventually comes to favor the MBF-P03 Gundam Astray Blue Frame as his personal mobile suit, modifying and upgrading it constantly to better suit his needs.
Elijah Kiel is a Coordinator and Gai's wingman, he pilots a custom ZGMF-1017 GINN and eventually a ZGMF-1001 ZAKU Phantom, each with a blade-like head crest and a "2" incorporated on its Serpent Tail emblem. Elijah's GINN has great sentimental value to him, so he continues to pilot the GINN even when it becomes greatly outdated: in fact, he switches to his new ZAKU only because his GINN was badly damaged. The LV-ZGMF-X23S Vent Saviour Gundam is his latest MS.
For a period of time, he was with ZAFT: although he is a Coordinator, he does not possess the superior physiology of Coordinator, so his MS maneuvering skills are poor. Through the experiences he gained on the battlefield as a mercenary, however, he polished his maneuvering skills, and has improved his combat skills substantially.
This 6 years old girl is the highly intelligent daughter of Loretta Adja. Because of her background, she possesses adult-like judgement and mental toughness, serving as a liaison to Serpent Tail's clients. It is currently unknown if she is a Coordinator or a Natural.
Explosives Expert and Tactician, Loretta is the only woman member of Serpent Tail. She is very popular among the mercenaries and is the mother to Kazahana Adja. She is a Natural and a former member of the Earth Alliance.
The captain of Serpent Tail's Laurasia-class frigate, Reed is a Natural and former Earth Alliance intelligence operative. He still retains contact with the EA and is also a known alcoholic.