The new Deadpool 2 trailer makes it very clear X-Force isn’t just in the Merc With the Mouth’s new movie; they’re crucial to the story, in which Cable (Josh Brolin) wants to kill a kid, and it’s up to Deadpool (Ryan Reynolds) to assemble a team that can protect him from the time-traveling mutant. If you don’t know an X-Force from an X chromosome, here are all the important details. And yes, there will be a test at the end, so pay attention.

The Original Team

Marvel

The first X-Force team was formed in 1991 as a spinoff from another X-Men series, The New Mutants (which is also in the process of being turned into a movie by Fox). The New Mutants were a group of young mutants taught and trained by Professor Xavier to someday become X-Men. Basically it was X-Men: The Next Generation; they even had their own weird robotic character who didn’t understand humanity (Warlock, who isn’t in X-Force as far as we know, so let’s just move on).

The first volume of New Mutants lasted 100 issues; over time, the characters aged, got a new headmaster (Magneto, after he gave up his villainous ways and took over Xavier’s School), and eventually grew too old to qualify as “new” mutants. In New Mutants #100, the team broke up, with several members leaving the Xavier School to join Cable in the more militaristic group he called X-Force; the initial lineup, created by writer Fabian Nicieza and artist Rob Liefeld, included former New Mutants Cannonball (who can fly and is nigh-invulnerable when he does so), Boom Boom (who creates energy bombs), Warpath (he’s, like, strong and durable he also has, like, lots of knives), along with Domino (or a shapeshifter pretending to be Domino, but let’s not get caught in the weeds here), Feral (werewolf-y lady), and Shatterstar (dude from another dimension with enhanced strength, speed, and lots of swords). That team existed for about a decade, with some characters coming and going but the basic concept remaining largely the same; a more proactive (and slightly more violent) version of the X-Men.

Reality Stars

Marvel

The team’s first major shakeup came in 2001, when the original team was seemingly killed off (they all survived, because comics) and an entirely new team adopted the X-Force name. Peter Milligan and Mike Allred’s X-Force had a drastically different tone (superhero satire) and visual style (brighter, and more colorful), and it followed a different group of mutants who wanted to use their celebrity as big-time superheroes to become media stars. This X-Force, one of the most unusual X-Men comics Marvel’s ever published, included members like Mr. Sensitive (two antennae gave him super senses), the Anarchist (acid sweat), the tragically named U-Go Girl (teleportation), and a mysterious floating green blob named Doop (he’s a green blob). After about a year, this X-Force’s comic was replaced by a new book called X-Statix with the same cast and creators. The new book lasted a few more years before its eventual cancellation in 2004.

Wolverine’s X-Force

Marvel

Of course, nothing stays dead for long in comics and a few years later the X-Force comic was revived with a new lineup. After a few mini-series (including one by team co-creators Nicieza and Liefeld), X-Force returned as an ongoing comic in 2008. Instead of Cable, Wolverine was now in charge, tasked by X-Men leader Cyclops with creating a sort of black ops team that could get its hands dirty in ways the main team could not. He put together a group of extremely pointy and stabby mutants; Warpath, Wolfsbane (a different werewolf-y lady), and Wolverine’s female clone X-23. The book proved more popular, and lasted for several years, with more mutants like Domino (her literal mutant power is “good luck”) and Angel (razor-sharp wings) joining the book.

This X-Force eventually turned into Uncanny X-Force with a slightly expanded roster featuring Psylocke (whose mental powers materialize in the form of, what else, big energy swords), Fantomex (he can create illusions and has, wait for it three brains), and, for the first time in team history, Deadpool (please tell me I don’t have to explain who Deadpool is). That book lasted for 35 issues, much of its run devoted to finding and killing a new version of the evil mutant Apocalypse.

Two X-Forces

By 2013, there had been a bunch of different X-Forces, but only one at a time. That year, Marvel launched two simultaneous books; a new Uncanny X-Force featuring Psylocke and her allies, and a competing Cable and X-Force series, in which a fugitive Cable goes on the run with his allies (they are all helpfully named in the image above). The two series eventually and inevitably crossed over, before they were combined into one final X-Force book in 2014 featuring Cable, Psylocke, Marrow (she uses her bones as throwing weapons, which is so gross), and Fantomex. (Seriously! Three brains!) That series lasted for just 15 more issues before ending in February of 2015.

Deadpool 2’s X-Force

Fox

That brings us to today and that new Deadpool 2 trailer, which introduces a very different version of X-Force. Instead of being led by Cable, these guys want to take him down (or at least stop him from killing someone). Beyond Wade Wilson and Zazie Beetz’s Domino, it’s not entirely clear who is on this team. Terry Crews is there but we still don’t know who he’s playing; I’ve read speculation that he’s Shatterstar, but the guy just behind Deadpool’s left shoulder in the photo above is wearing headgear that looks a lot more like the comic-book version of that character. It’s more likely Crews is playing a mutant named Bedlam, based on both Crews’ costume and this very brief glimpse of a headshot with his name on it from the trailer.

Fox

That’s comedian Rob Delaney in the “Peter” headshot there. The most famous Peter in X-Men history is Colossus (real name Piotr Rasputin), who is featured in this trailer along with Negasonic Teenage Warhead from the first Deadpool, although neither one appears in that X-Force group shot above. Could Delaney play the human version of Colossus? I guess it’s possible, but I would bet instead he’s playing Pete Wisdom, another occasional X-Men ally who can throw energy blades from his fingers, and was usually portrayed in exactly the sort of dark suit and tie as in that picture.

Fox

And then there’s the character played by Shioli Kutsuna with the energy weapon. That could be Surge, a recent member of New Mutants and New X-Men teams. And let’s not forget the two guys sitting next to Domino on the helicopter in this shot, including IT’s Bill Skarsgard. I have no clue who they might be.

Fox

(The guy in the back has a great mustache, but I’m not familiar with any X-Force members with super mustache powers.)

We’ll probably know a lot more about these X-Force members before the movie comes out; they’re supposedly set to star in their own spinoff movie (which will also feature Deadpool and Cable) in the near future. Deadpool 2 opens in theaters on May 18.