- "Pretty much the only rule for rookies on the Blue Team is: don't kill the leader."
- —Church in Brass Tacks
The members of Blue Team are the rivals of the Reds, and the ones stationed at Blood Gulch Outpost Alpha (Blue Base) are the most known. However, there are other outposts with members of the Blue Team, such as Outpost 17-A (in Valhalla) and Outpost 28-A (in Rat's Nest). The story primarily revolves around the activities of the Blue Team, and throughout the years they were the only team to have suffered casualties.
Church was the Blood Gulch Blue Team's self-appointed leader, after the death of their leader, Captain Flowers. He is foul-mouthed, often stressed, and very easily angered, especially by his own team members. Church uses a sniper rifle as his main weapon, despite being a terrible shot. In fact, Church hitting anything with a bullet is described by Washington as "unbelievable". The only 3 things he's successfully hit are Caboose's toe with a pistol, Wyoming in the chest with a sniper rifle (though Wyoming quickly distorted time, thereby ensuring it never "actually" happened), and the Meta's leg in an impossible sniper shot, although Washington joked that he didn't call it, so it doesn't count (alluding to rules of billiards). During the events of Reconstruction, Church is revealed to be the Alpha AI. His armor color is cobalt.
Tucker is juvenile, lazy and increasingly obsessed with sex. Later in the Blood Gulch Chronicles, he develops a constant habit of spouting his catchphrase "bow chicka bow-wow" whenever he hears a sentence that sounds like/is a sexual innuendo and is willing to travel great distances (usually a few hundred feet) to say it, much to the annoyance of the other team members. Based on his first name, Church asks Tucker if he's black. Tucker offers no real answer, but later evidence suggests that he may, in fact, be black. Tucker is also very long sighted, being able to see Donut from the Blue base without the aid of a sniper rifle (a skill he was forced to master due to never being allowed to use the sniper rifle). Following Church's death, especially having sole use of the sword, Tucker turns out to be one of the few genuinely skilled soldiers among the Reds and Blues. His armor color is aqua.
Caboose is the kind-hearted rookie of the blue team who starts off as merely incompetent. However, as the series progressed, his mannerisms have increased far from just being stupid all the way to questionably unstable. He has a deluded imagination and often perceives reality far differently from the other characters. Caboose's antics are a major source of humor within Red vs. Blue; he is arguably the source of most of the show's humor. His armor color is blue.
Kaikaina (nicknamed "Sister") is the ditzy, bisexual girl of the group who is just as, if not more so, sex obsessed as Tucker. While she is the younger sister of Grif, she was enlisted into Blue Team to be the replacement member for Butch Flowers after his death. A running gag would involve her saying something extremely sexual or disturbing and one of the other characters would follow up with "Yeah...Wait, what?" While she originally only appeared in Season 5, she would later return to be a mainstay again in Season 16. Her ditzy personality would also later be reduced, although her sex obsession is just as strong as ever. Her armor color is yellow.
The last member of the Blood Gulch Blue team is Tex. Although actually a mercenary hired to help them in the war, she is considered a part of the team in most situations. She is regarded as a "mean bitch" by most of the Blood-Gulch soldiers and is greatly feared between both teams. Despite this, she did see the Blues as friends before her death. Her scary demeanor was helped by Project Freelancer. She was also a former girlfriend of Church. Her armor color is black.
Though only officially joining the Blues in season 8, Sarge accused Washington of being a Blue not long after his introduction in season 6. He has now become a very significant team-member. Originally a kind and quirky turned cold-hearted agent from Project Freelancer, Washington found a true sense of belonging when he met the Reds and Blues. His armor color has mainly been steel with a yellow tint, though it was colbalt for a while in order to avoid arrest by impersonating Church.
Prior to becoming an agent of Project Freelancer, Carolina had lost her mother during the Great War at age 6, which sent her father into a deep depression. As she got older, she developed a romantic relationship with York, who would eventually be with her as a fellow agent in Project Freelancer. Since then, she has become one of the most combatively skilled characters in the series, being only surpassed by Tex. Carolina has now developed a relationship with the Blood Gulch soldiers, becoming an official member of Blue Team, and has moved on with her life after the events of Season 10.
Since then, many other characters have since joined the Blue Team as the series progressed, but the team also suffered far more casualties than the Red Team. It was later discovered both the Blue and Red teams were assigned as part of an experiment of Project Freelancer. Also, the Blues were mostly the ones to advance the story in the series and provided insight, such as Church's knowledge of Project Freelancer and its staff, Tucker's Sword being the key to vital alien artifacts that saved the day, or the Epsilon Incident which involved Washington and Epsilon. This was joked upon by Simmons, who noted all Red team usually does is talk about guns and food.
Other members who were once affiliated with the Blood Gulch Blue Team.
Other members of the Blue Army that are unaffiliated with the Blood Gulch Blue Team.
- Less than half the members of the Blood Gulch Blue Team are human. Having a total of 12 members, 5 are human, 6 are A.I., and 1 is an alien.
- The Freelancers seem to have a more positive relationship with the Blues than the Reds: Florida was their commanding officer, Tex has (mostly) aided the Blues, Wash eventually joined the team, and Carolina shows more respect towards them than she does the Reds.
- Almost of the leaders of the Blood Gulch Blue Team have had a previous affiliation with Project Freelancer. Both Flowers and Wash were once Freelancers, Church was the Alpha A.I., and Epsilon is a fragment of the Alpha. The only exception is Tucker.
- Interestingly, each former leader of Blue Team has died due to his successor's actions. Flowers's (first) death was a result of Church injecting him with Aspirin; Wash activated the EMP at Command, thus destroying Church/the Alpha.
- Simmons, a Red Team soldier, has joined the Blues on occasions, but eventually returns to the Reds. Interestingly, he ties with Tucker for having the highest rank on the team; thus, he can "technically" take command of the team when he joins them.
- During The Blood Gulch Chronicles, Doc, a medic who's neutral, spends more time with the Blues than the Reds. Despite this, he states he is still neutral during this time.
- Tucker, Caboose, and Sister are the only remaining members of the original Blood Gulch Blue Team to still be currently active.
- Sister is the only character from Blood Gulch Blue Team to not have killed anyone in a canon episode.