The CW has been building up its DC Comics shared television universe over the past few years, first with the launch of Arrow, then with the show's spinoff series, The Flash, and now with the network's upcoming third comic book superhero program, Legends of Tomorrow. As part of The CW's shared DC Comics universe, characters from both The Flash and Arrow have shared the small screen a number of times, including their large crossover events each season -- the most recent of which pit Team Arrow and Team Flash against Vandal Savage (Casper Crump), who will go on to be the main villain of Legends of Tomorrow.
Aside from the larger events, Arrow and The Flash have also featured smaller crossovers, such as John Diggle (David Ramsey) and Lyla Michaels' (Audrey Marie Anderson) upcoming trip to Central City in order to recapture King Shark. Now, in keeping with this CW/DC television universe tradition, it seems Legends of Tomorrow will include some of these smaller crossovers with the Arrow and The Flash heroes during its first season as well.
"It’s intermittent throughout. Because they’re a band of time traveling rogues, it’s harder for Arrow and Flash to be connected story wise to it throughout the season. That being said, if you know the histories of Arrow and Flash, it should be extra fun in its own way as we delve deeper and deeper into the characters lives."
Some crossovers have already been confirmed for Legends of Tomorrow, like the appearance of Ra's al Ghul (Matt Noble) -- who met his death in season 3 of Arrow -- as well as Oliver Queen's (Stephen Amell) current foe Damien Darhk (Neal McDonough), and Barry Allen's (Grant Gustin) friend/ally Cisco Ramon (Carlos Valdes). Additionally, Legends of Tomorrow executive producer and showrunner Phil Klemmer said there is a "100 percent chance" the show will feature older and/or younger versions of Oliver and Barry: "We will have a couple marked crossover moments that hopefully will keep people satisfied."
Aside from the appearance of the Green Arrow and The Flash, Legends of Tomorrow is already combining characters from its fellow CW series to create a large cast: Ray Palmer/The Atom (Brandon Routh) and Sara Lance/White Canary (Caity Lotz) from Arrow; Leonard Snart/Captain Cold (Wentworth Miller), Mick Rory/Heat Wave (Dominic Purcell), as well as Martin Stein (Victor Garber) and Jay Jackson (Franz Drameh) a.k.a. Firestorm from The Flash. Additionally, though Kendra Saunders/Hawkgirl (Ciara René) and Carter Hall/Hawkman (Falk Hentschel) appeared on both shows, they will be joining Rip Hunter (Arthur Darvill) as the newest heroes in The CW's shared universe.
Though we don’t know much about many of these planned crossovers, Berlanti’s comment on knowing the histories of Arrow and The Flash may hint that the Legends will revisit past events from those two series, or perhaps offer insight into the heroes’ futures. But, with so many characters sharing the screen in Legends of Tomorrow, it seems likely the cameos and crossovers with Arrow and The Flash will be on the smaller side.
That being said, though, the prospect of seeing different iterations of known characters from within The CW's DC universe, whether from the past or future, is exciting. The Flash has dealt with time travel in the past, and will be featuring Earth-2 alternate versions of its main characters in an upcoming episode. But, with Legends of Tomorrow focusing on a number of different time periods, both from the past and future, it may well depict new and compelling sides to already established heroes (and/or villains) -- adding an extra bonus for fans of The CW DC universe who watch Legends of Tomorrow.
The Flash will return on Tuesday, January 19, 2016, while Arrow will return on Wednesday, January 20, 2016 and Legends of Tomorrow will see its series premiere on Thursday, January 21, 2016.