Arriving in December over three nights, this year's Arrowverse crossover, "Elseworlds," will be a first in many respects, with the introduction of Ruby Rose as Batwoman, and Elizabeth Tulloch as Lois Lane. But it will also be the first time the heroes of DC's Legends of Tomorrow won't be involved, which is just fine with showrunner Phil Klemner.

"I was happy to have sit this year out just because we only have 16," he told The Hollywood Reporter, "and our run of episodes was so tight and integrated ... I'm glad we got to do a straight run this year."

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Although discussions have already begun about the 2019 crossover, Klemner remains in the dark about specific plans. "There's already a loose shape for it even though this year's crossover isn't done by a long shot," he said.

Legends of Tomorrow was itself born from the 2013 crossover "Legends of Today/Yesterday," which served as the series' backdoor pilot. Since then, the Legends have regularly appeared in the crossovers, typically in small groups before the whole team comes together during the back half of the event. Last year's crossover, "Crisis on Earth-X," saw a major shakeup in the Legends cast with the death of Martin Stein, which led to the eventual departure of Jefferson Jackson.

Returning to The CW on Monday, Oct. 22 at 9 pm ET/PT, DC’s Legends of Tomorrow stars Caity Lotz as Sara Lance/White Canary, Dominic Purcell as Mick Rory/Heat Wave, Brandon Routh as Ray Palmer/Atom, Nick Zano as Nate Heywood/Steel, Maisie Richardson-Sellers as Amaya Jiwe/Vixen, Tala Ashe as Zari Tomaz, Matt Ryan as John Constantine, Jes Macallan as Ava Sharpe and Courtney Ford as Nora Darhk.