The third season of the American television series Legends of Tomorrow, based on DC Comics characters, premiered on The CW on October 10, 2017, and ran for 18 episodes until April 9, 2018.

The season follows the Legends, a dysfunctional team of time-traveling superheroes and anti-heroes, and their mission to correct their unintentional anachronisms.

The season was produced by Berlanti Productions, Warner Bros. Television and DC Entertainment, with Phil Klemmer and Chris Fedak its showrunners.

Principal cast members Caity Lotz, Brandon Routh, Victor Garber, Franz Drameh, Maisie Richardson-Sellers, Amy Pemberton, Nick Zano, and Dominic Purcell return from previous seasons and are joined by new cast members Tala Ashe and The Flash alumnus Keiynan Lonsdale.

They are forced back into action as deputized members of the Time Bureau, however, unaware that Rip is planning to use their often-destructive tendencies for a threat bigger than the anachronisms.

Members of the teams face off against Earth-X Metallo, while Felicity and Kara are cornered by Dark Arrow before Oliver saves them.

Caitlin, Amaya, and Zari infiltrate the Nazi timeship Wellenreiter to disable its shields so Harry and Cisco can destroy it with the Waverider.

[75] Co-creator Marc Guggenheim said that he wanted to have the Legends visit new locations, including Golden-Age Hollywood and Victorian London.

As opposed to the villains of seasons one and two, Mallus was an original character created for the series rather than adapted from DC Comics.

[84] Returning series regulars from the previous season included Victor Garber, Brandon Routh, Caity Lotz, Franz Drameh, Maisie Richardson-Sellers, Amy Pemberton, Nick Zano and Dominic Purcell as Martin Stein, Ray Palmer, Sara Lance, Jefferson Jackson, Amaya Jiwe, Gideon, Nate Heywood and Mick Rory, respectively.

[87][88] Guggenheim explained that part of the motivation for adding the Muslim character, Zari Tomaz, to the series was the "political climate" in the United States after the 2016 elections.

[94] While Garber wanted to resume his career in Broadway theater;[95] Drameh's exit was a creative decision,[96] and he returned in the season-finale "The Good, the Bad and the Cuddly".

[30] Several actors returned in their roles from other Arrowvverse series as recurring characters, such as Neal McDonough as Damien Darhk,[30] David Sobolov as the voice of Grodd,[100] and Christina Brucato as Lily Stein.

[31] Tracy Ifeachor was cast as Jiwe's granddaughter Kuasa, replacing Anika Noni Rose (who voiced the character in the animated web series Vixen).

[111] In May 2017, CW president Mark Pedowitz announced plans for a four-show Arrowverse crossover event consisting of Supergirl, The Flash, Legends of Tomorrow, and Arrow.

The website's consensus reads: "DC's Legends of Tomorrow lightens up the tone in its third season while spotlighting adventurous plots and a distinct sense of humor.

Scheeden criticized the season's main villain, saying that Mallus did not properly pay off the buildup, and called the totem plot line "boring".