By now you have no doubt been deafened by the infinite squees of a billion fans reacting to the “leaked” trailer for Suicide Squad. If you watched it and merely wondered why everyone was so excited about this new Will Smith picture, this is a brief intro to the comics and characters the movie is based on. The titular squad is a black-bag strike force composed of captive supervillains compelled into the government’s service. There have been many iterations with a frequently rotating roster of roustabouts and scoundrels from the DC universe, and the film version appears to have borrowed from many of them while adding a few new faces to the mix. Here’s a quick rundown of the characters revealed in the trailer, from least dangerous to most deadly:

No, not the heavy metal band, although I’m sure he’s the kind of guy that would listen to them. Slipknot is a mercenary who is really skilled in the use of rope. He even invented a formula for unbreakable rope that he uses to strangle people. Despite “guy who ties unbreakable nooses” being the entirety of his thing, poor Slipknot has been repeatedly sent to fight enemies that are undeniably choke-proof, like an army of robots and a dude made of living fire, and has not fared well. When he tried to run away from the squad, an implanted explosive took off his arm. Most of his recent appearances are either in prison or on the Suicide Squad, but now he can choke people even harder with his sweet bionic arm.

Both Digger Harkness and his son, Owen Mercer, have worn this title. They both carried on criminal careers based on throwing lots of trick boomerangs at the Flash and served on the Suicide Squad at one time or another due to their moral flexibility and experience in metahuman combat, so it could be either one. But the mutton chops and pronounced Aussie accent lead me to assume the movie version is going to be Boomerang Senior, who was often described as too dangerous and unstable even by Suicide Squad standards. Digger not only had the requisite problems with authority, he often jeopardized missions with his drinking, picked fights with his teammates, and even left one of them to die just because he didn’t like her. He also convinced Slipknot to run away just so he could see if the bombs inside them were live. Every team needs a heel, that guy that everyone else hates, and here it's usually Captain Boomerang. Even among villains, Digger has few friends.

A former gangbanger, El Diablo used his pyrokinetic abilities to enflame his enemies with his mind. One day he burned down the home of some men who owed him money, and when he discovered the bodies of innocent women and children among the rubble he was so ashamed of what he’d done that he surrendered to the cops without a fight. Diablo is the one who looks out for the civilians and often tries (and fails) to convince his teammates to take a less lethal approach. He joined the squad in hopes of atoning for his past sins, but hasn’t yet realized that the people pulling the strings aren’t interested in his redemption—they want him to keep doing the bad things that got him there until he dies “in the line of duty.” Although capable of incinerating entire buildings full of people just by thinking about it, Diablo is trying really hard to be a better man and is reluctant to unleash his full power.

Another Suicide Squad legacy, the Flags were typically the “legitimate” military overseers in the field. Flag Senior was a World War II hero and leader of the first Suicide Squadron. After he died, his son took up leadership of the new team formed by Amanda Waller. Flag Junior didn’t want the job, resents the criminal scum he is forced to work with, and seriously hates Deadshot in that special way reserved for someone who reminds you too much of yourself. Rick Flag Jr. likes to remind his teammates just how expendable they are, and is more than willing to sacrifice them to achieve the objective. The modern setting suggests this version is Junior, but it remains to be seen if his family history will get any mention. Both Flags were capable combatants and psychotically rabid patriots who would slit a child’s throat if they thought it would somehow serve Uncle Sam.

Tatsu Yamashiro was a beautiful Japanese girl beloved by two brothers, and when she chose one the other bitterly vowed revenge. The scorned brother went on to become a feared enforcer for the Yakuza before returning with two swords to challenge his brother to a duel for his wife. Poor Tatsu awoke to find her husband being murdered by his brother and their home in flames. She disarmed the assailant and was about to go rescue her children when she heard the voice of her deceased husband telling her they were already lost. Tatsu sought further training from an old master before embarking on a quest to avenge her dead husband, whose soul resides in her sword and gives her tips on killing Yakuza. While Katana is ostensibly a hero, her willingness to slay evil-doers has often put her at odds with the rest of the masked crusader community (particularly Batman), because you don’t carry a sword called Soultaker if you’re just bruising egos. That’s possibly why she’s in Belle Reve at the start of the movie. Katana has never been a member of the Suicide Squad in the comics, although she often served with the Outsiders, a kind of superhero black-ops team.

Waylon Jones was born with a genetic disorder that caused him to become more and more reptilian throughout his life. When first encountered by Batman, Jones was an up-and-coming kingpin, almost beating the Joker for control of the Gotham underworld. They only called him Croc because of his scaly skin condition. But over time, his nickname has become increasingly accurate as he devolved into a bestial monster with a taste for human flesh and the strength to punch through concrete. No longer a criminal mastermind, Killer Croc is often hired or manipulated by smarter supervillains into serving as a mid-level boss fight for Batman while they carry out the real caper. Though often defeated, Croc is among the Dark Knight’s most dreaded sparring partners, a raw force of nature that is not easily overpowered. Although he has never served on the squad in the comics, he has appeared in many of the Batman cartoons and was likely swapped in as a slightly more familiar replacement for King Shark, another mutated beast-man that eats people.

Harley Quinn holds the distinction of being the first character created for an animated series to become a part of the comics’ canon. Dr. Harleen Qunizel was a psychiatrist at Arkham Asylum who fell in love with her patient, the homicidal maniac known as the Joker. After helping him escape, she became his on-and-off lover and ultimate henchgirl, someone who got all his crazy jokes and could go toe to toe with Batman and Friends. Despite their bizarre chemistry, Harley and the Joker have had the kind of tumultuous and abusive relationship you would expect from two psychopaths. They have even attempted to murder each other a few dozen times, but they never seem to be able to stay apart for long. In the rebooted DC universe, Harley serves on the squad until she hears about the death of the Joker and betrays the team to go searching for the mortal remains of her beloved Mr. J. She eventually reinvents herself as a hero, going on adventures and fighting villains with Power Girl. The movie seems to have a different take on how Harley met Joker, one that looks a little more like Stockholm Syndrome than Mad Love, but the relationship will likely still be a large part of the character’s arc. Watching these two interact is always morbidly fascinating.

Deadshot is basically the antithesis of Batman: no regard for human life, a fondness for guns, and available to the highest bidder. Floyd Lawton is the top assassin in the DC universe despite having no powers, and is frequently described as the guy who never misses. Precise enough to hit a bullet with another bullet and tough enough to trade punches with the Bat, Lawton was an ideal recruit for the Suicide Squad, and typically serves as their unofficial commander in the field. Supervillains may be notorious for not following orders, but most could respect that Deadshot is just trying to get them through the mission alive so he can actually enjoy his reduced sentence. Lawton’s also the one typically charged with retiring teammates who have outlived their usefulness. He knows the game well and tries to play it to his advantage, but is always inevitably outsmarted by Amanda Waller. Although he could certainly take her one on one, Waller is smart enough to never give him the chance. They’ve threatened to kill each other so many times it's practically how they say hello. Considering who he’s locked up with in the movie trailer, it’s likely he was put there by Batman, a common theme amongst many of the characters.

Poor June Moon wandered into the wrong room during a costume party at a haunted castle (WHY?) and ended up as the host for a malevolent demon from another dimension. It manifests as an alternate personality, the Enchantress, who is a powerful sorceress with a real nasty streak in her. Although June tried to turn her newfound magical prowess to a good cause, using the power only enabled the demon within. The Enchantress is basically the team’s Hulk: her magic can cripple armies, but every time she uses it she risks becoming an even bigger problem than the one she’s fighting. With the ability to threaten all life on Earth and very little control over it, one has to wonder why anyone thinks sending the unhinged sorceress on top secret missions is a good idea, but it certainly raises the stakes for some good storytelling. She eventually went full evil and almost killed Supergirl, then joined an army of villains that declared war on all of reality. Moon joins the Suicide Squad because Waller promises they will help her control her darker side, but in truth, Deadshot has orders to put her down if she ever starts to lose it. When she inevitably does, it takes the entire Justice League to stop her from destroying the world. While the rest of her team certainly aren’t saints, she’s the only one who could actually end existence from inside her cell if she lost her temper. Not a woman to trifle with.

“The Wall” has long been one of the most feared non-powered individuals in the DC universe. A polarizing figure in the American government, Waller was frequently the head of black ops outfits and research projects on how to fight metahumans, and at least one organization that did both. She was ruthless so she was often tasked with handling ruthless people. She was the one who restarted the Suicide Squad, recruited its members, planned its missions, and ultimately took the fall when the whole thing went sideways. As she confesses in the trailer, she is a master manipulator and schemer, always five moves ahead. Waller knows who Batman is and has at least three contingency plans to kill Superman on standby. Few things surprise her, and when they do she’s not afraid to grab a weapon and get her hands dirty. The government often comes to Waller to solve superpowered problems, and then condemns her actions once the world is safe. Although she has been imprisoned many times for the squad’s operations, she never stays locked up for long. When shit gets a little too real, someone at the White House always knows it's time to pardon the Wall so she can get back to defending them.