The new CW superhero spinoff "DC's Legends of Tomorrow" features recurring characters from "Arrow" and "The Flash" as well as a couple who only first showed up in last month's crossover event. Tonight, they all come together under the direction of a time-traveler to defeat an immortal villain intent on destroying humanity 150 years from now.

HNGN has put together a handy little guide to keep all the characters straight and serve as a reminder to which ones have reformed their villainous ways and which are realizing their true heroic identities.

"DC's Legends of Tomorrow" premieres tonight, Jan. 21 at 8 p.m. on The CW.

Ray Palmer aka the Atom (Brandon Routh) - Billionaire inventor Ray Palmer made his debut in the season three premiere of "Arrow." He's the creator of nanotech which allows him to shrink targets and his A.T.O.M. exosuit. He also shared a short romance with Felicity Smoak, before letting her go so she could pursue a relationship with her true love, Oliver Queen.

Sara Lance aka the White Canary (Caity Lotz) - The trained assassin Sara Lance first appeared in the season two premiere of "Arrow." She learned to fight as part of the League of Assassins. She dated Oliver Queen and was the one who got resurrected in the Lazarus Pit, which brought back fan favorite John Constantine (Matt Ryan) who used his magic to reunite Sara with her soul.

Professor Martin Stein (Victor Garber) and Jefferson "Jax" Jackson (Franz Drameh) aka Firestorm - Ronnie Raymond (Robbie Amell) first took up the mantle as Firestorm when he merged with Professor Steing following a blast caused by the S.T.A.R. Labs particle accelerator early in the first season of "The Flash." They later separated but re-merged a few more times until Ronnie's death.

He finds a new partner in Jax, who has the superior body that merges nicely with Stein's brilliant mind.

Leonard Snart aka Captain Cold (Wentworth Miller) - Leonard Snart appeared solo without his pal Mick Rory in his first appearance on "The Flash" in the episode "Gone Rogue" when he got his hands on the cold gun. He later teams up with his old friend Heat Wave to kill The Flash (unsuccessfully, of course).

In his final appearance, Snart tips off Barry (aka The Flash) of a possible assassination attempt on his life and then gets out of town.

Mick Rory aka Heat Wave (Dominic Purcell) - Mick is a pyromaniac with a heat gun, who teams up Captain Cold in two first season episodes of "The Flash." In his last appearance, he was in a police truck on his way to prison before Snart's sister broke him out.

Kendra Saunders and Carter Hall aka Hawkgirl (Ciara Renée) and Hawkman (Falk Hentschel) - Kendra Saunders first arrived to "The Flash" as a barista at CC Jitters. She and Hawkman first took on their true identities in the "Arrow"-"Flash" crossover event "Legends of Today" and "Legends of Yesterday." They both share a spiritual connection the villain, Vandal Savage.

Rip Hunter (Arthur Darvill) - The time-traveling Rip Hunter will make his debut in "DC's Legends of Tomorrow" when he assembles the aforementioned heroes and villains to defeat Vandal Savage before he sets his plans of destroying humanity into motion.

Vandal Savage (Casper Crump) - The immortal villain Vandal Savage first revealed his evil plot in the "Arrow"-"Flash" crossover event. He will not claim victory until he has unleashed total chaos and utter destruction on humanity.