DC's Legends of Tomorrow won't be part of this year's Arrowverse crossover Elseworlds. The Legends played key roles in the previous crossover events: 2016's Invasion!, where they joined the other superheroes in fending off an alien attack by the Dominators, and 2017's Crisis on Earth-X, where Nazi doppelgangers from a fascist 53rd Earth attempted to literally steal Supergirl's (Melissa Benoist) heart and conquer Earth-1. However, the time-traveling heroes won't be in 2018's Elseworlds.
This year's Elseworlds crossover will bring together the titular heroes from Supergirl, Arrow, and The Flash to face a new threat to reality that will also introduce Batwoman (Ruby Rose) and Gotham City to The CW's shared superhero universe. Also in Elseworlds will be the return of Superman (Tyler Hoechlin), the debut of Lois Lane (Elizabeth Tulloch), and even John Wesley Shipp once again playing The Flash from his 1990 CBS series. They're facing off against malevolent Arkham Asylum doctor John Deegan (Jeremy Davies) and an otherworldly being called The Monitor (LaMonica Garrett).
So while the rest of their fellow superheroes try to deal with The Flash (Grant Gustin) and Green Arrow (Stephen Amell) switching bodies, here are the real world and also the in-universe reasons why Legends of Tomorrow is sitting out Elseworlds.
The Reasons Legends of Tomorrow Are Skipping Elseworlds
Legends of Tomorrow's absence from Elseworlds mostly breaks down to logistics. With so many superheroes involved, which includes special guests like Batwoman, Superman, Black Suit Superman, Lois Lane, and the 1990 Flash, there would be little more for a cast as large as the Legends to do besides make token appearances and say a few lines of expository dialogue. In addition, executing the annual crossover, which means coordinating the actors, crews, and production staff across four series is extremely difficult. It lessened the logistical burden for the entire production to limit the crossover to three series.
Ultimately, the Arrowverse's brain trust opted to let the Legends keep doing their own thing, which suits Legends of Tomorrow's showrunner Phil Klemmer just fine:
"I was happy to have sit this year out just because we only have 16 and our run of episodes was so tight and integrated. [Crossovers are] always a blast but it is a departure. I'm glad we got to do a straight run this year."
The Legends are kind of the outliers of the Arrowverse anyway so it makes sense that they miss this year's big crisis. However, while the series isn't part of Elseworlds, the crossover is bound to contain several surprises and it's possible one of them might involve a Legend or two.
Instead, Legends Is Having Their Own Crossover... With Themselves
Of course, the Legends of Tomorrow have their own massive problem to deal with, thanks to John Constantine literally breaking time itself. The British warlock did a forbidden thing and altered a fixed point in time, sparing his lover Desmond Leveau from banishment in Hell under the thrall of the demon Neron. In doing so, Constantine created a time ripple that struck all of the Legends and the agents of the Time Bureau. As the Legends now race to repair the damage Constantine caused, they will encounter alternate versions of themselves across alternate timelines. Essentially, they're having a crossover... with themselves.
The preview for Legends of Tomorrow's midseason finale "Legends of To-Meow-Meow" teases Sara Lance (Caity Lotz), Ava Sharpe (Jes Macallan), and Gideon (Amy Pemberton) becoming a version of Charlie's Angels, the heroes will revisit previous events in season 4 like when they faced a killer unicorn at Woodstock 1969, and they will even meet puppet versions of themselves, all while Zari Tomas (Tala Ashe) is stuck as a cat.
So, it's pretty much a typical week for Legends of Tomorrow, who deal with enough bizarre chaos in their regular adventures that they really don't need to be part of Elseworlds.
DC's Legends of Tomorrow's midseason finale airs Monday, December 10th @ 9 PM on The CW.