The 11 Biggest Reveals From The CW's 'Arrow'-verse Crossovers Over the Years

From the very first time that 'Arrow' and 'The Flash' crossed over with "Flash vs. Arrow," the 'Arrow'-verse has used the annual events to reveal some big game-changing twists.
Sergei Bachlakov/The CW

One of the best things about comic books is how easily — and often — the big-name characters can team up for all kinds of world saving, large and small. When all it takes is paper and ink, the opportunities for superhero crossovers are endless. But in a medium like television, where budgets, scheduling and red tape can get in the way, it takes a lot more than that to bring the big headlining characters together onscreen.

That's one of the reasons why The CW dedicates one week a year for its annual Arrow-verse crossover. During the course of one week and, across multiple episodes, with characters, sets and crews from a number of series, developed and shot over the course of one intensive month, the annual event brings the best facets of comic books to the screen. Characters like Green Arrow (Stephen Amell), the Flash (Grant Gustin), Supergirl (Melissa Benoist) and more combine their talents and contrasting, often competitive personalities resulting in big action, spectacle and, most of all, comedy. The crossover events so far have been "Flash vs. Arrow," "Heroes Join Forces," "Invasion!" and "Crisis on Earth-X," leading up to this year's "Elseworlds" event.

But it's not all fun and games — the producers of the Arrow-verse series also make sure to drop some game-changing twists in every annual crossover to make them can't-miss TV viewings. From Easter eggs with delayed explosive results to character/relationship evolutions to even introducing new series, every crossover so far has changed the Arrow-verse as fans knew it in both macro and micro ways. So in regards to this year's upcoming Batwoman (Ruby Rose) crossover, "Elseworlds," fans should expect the same treatment. 

Leading up to Sunday's debut of "Elseworlds," The Hollywood Reporter took a look back and ranked all the previous crossover reveals to see which one shook up the extended TV universe the most. Where will Batwoman's debut in "Elseworlds" fall?

11. Diggle and Lyla get engaged (again)

During the Arrow episode of the very first crossover event, "Flash vs. Arrow," Lyla (Audrey Marie Anderson) suffered injuries that landed her in the hospital. Diggle (David Ramsey) realized how much he still loved her and asked her to marry him (again). She, of course, said yes, and they'd later go on to get married and have a child together. They're still happily married on Arrow, so while this was a major piece of relationship evolution, it hardly came as a surprise since they had been married before and were already acting like their divorce never happened. Hence, the low ranking.

10. Vandal Savage lives to see another day (and series)

In the epic conclusion to "Legends of Yesterday," aka the unofficial debut of Legends of Tomorrow through the second Arrow and The Flash crossover, Vandal Savage (Casper Crump) appeared to have been killed in the big climax battle. But he had a whole new series to plague as the future Legends of Tomorrow big bad, so Malcolm Merlyn (John Barrowman) returned to the scene of the crime to scoop up Vandal's ashes and go on to bring the mystical killer back to life. This wasn't the biggest reveal, as fans knew Vandal would return in some capacity for the new Arrow-verse series after this crossover, but the fact that it was Merlyn to bring him back was definitely a head-scratcher.

9. The Ray makes his debut

During second half of the "Crisis on Earth-X" crossover, new Arrow-verse superheroes The Ray (Russell Tovey) and Citizen Cold (Wentworth Miller) made their triumphant debuts. The two gay heroes were in love with each other, bringing some more LGBTQ representation to the inclusive Arrow-verse. Plus, it allowed Miller to return to the Arrow-verse as a doppelganger of his original character, villain Captain Cold, but this time as the snarky, optimistic and romantic Leo Snart. While he and Ray were still happily together, Leo decided at the end of the crossover to stay with the Legends for a while, marking the beginning of Miller's last arc in the Arrow-verse.

8. The "mystery girl" makes her first appearance

At the time of "Crisis on Earth-X," viewers could tell that Jessica Parker Kennedy's "mystery girl" would play a big role on The Flash moving forward. Her creepy obsession and enthusiasm for Barry and Iris' (Candice Patton) wedding meant she knew them more than a random cater waiter should. But it wasn't until later on that season on The Flash that her identity as Barry and Iris' daughter from the future was revealed. Her Easter egg debut in "Crisis on Earth-X" was a pretty big twist, but having the payoff almost half a season later took away some of the shock at the time.

7. Dr. Stein realizes he had a daughter

After messing with the timeline on Legends of Tomorrow, Dr. Martin Stein (Victor Garber) discovered during The Flash's episode of "Invasion!" that he had a grown daughter of whom he didn't have any memories. This led to some really sweet and heartbreaking character development for Stein, but it's not the most shocking "secret child" reveal from the crossovers ...

6. Ronnie Raymond is alive ... but not well

The stinger scene at the end of "Flash vs Arrow," the first Arrow-verse crossover, revealed that Caitlin Snow's (Danielle Panabaker) late fiancé Ronnie Raymond (Robbie Amell) wasn't as dead as previously thought. He was shown to be a homeless man living on the streets of Central City, with some kind of fire metahuman powers that he couldn't control. He definitely didn't look good. No one on Team Flash knew he was still alive at this point, but his debut would kick into motion his journey toward getting the help he needed to figure out his FIRESTORM abilities and becoming a superhero, plus reuniting with Caitlin.

5. That double wedding

While the "Crisis on Earth-X" crossover started with Barry and Iris' wedding (before it got so rudely interrupted by Nazis), it ended with not one but two weddings. Having defeated the Earth-X Nazi doppelgangers, Barry and Iris decided to elope right then and there, with Diggle as their minister and Oliver and Felicity (Emily Bett Rickards) as witnesses. But Felicity decided that interrupting Barry and Iris' nuptials again was the perfect time for her and Oliver to also get married. The double-wedding was quite a happy note to end the crossover on, as it signaled the end to (most of) the relationship issues for WestAllen and Olicity. But many fans were disappointed that Oliver and Felicity's wedding was squeezed into an episode of a different show (it aired as a Legends of Tomorrow episode) and that Barry and Iris' happy moment was hijacked by another couple (even if it was their friends).

4. Tommy Merlyn returns

During "Crisis on Earth-X," fans were expecting evil doppelgangers from the Nazi-occupied alternate universe Earth-X. But the reveal that Earth-X Prometheus was none other than Tommy Merlyn (Colin Donnell) absolutely took the cake. Tommy hadn't been seen in the Arrow-verse since his heartbreaking death in the Arrow season one finale (aside from Oliver's vision of him in Arrow's 100th episode), and his few scenes as the evil Prometheus were chilling. If only his return lasted more than just a quick interrogation with Oliver before Tommy killed himself with poison. The reunion was too short-lived!

3. Stein dies

While fans were prepared to say goodbye to Stein as news of his Arrow-verse exit broke early, all hopes that he would have a peaceful swan song were crushed when he was killed during the "Crisis on Earth-X" crossover. In the second half, he was shot fatally during an escape from Earth-X. His death was even more of a gut punch because he had just figured out a way to separate himself from Jax (Franz Drameh) as FIRESTORM, leaving Jax to stay a superhero with the Legends while Stein retired to spend time with his family. Alas, he left both Jax and his family on a much more traumatic note, seemingly for no reason.

2. Oliver discovers he has a secret son

Obviously this Arrow reveal (in the Legends of Tomorrow introduction "Legends of Today" episode of The Flash) is the mother of all twists. But it was the payoff that was a year in the making after it was revealed that ...

1. Oliver has a secret son

In the very first crossover ever, "Flash vs. Arrow," fans were clued in on a huge secret: Oliver was a father. This is something that not even Oliver would come to learn until the next year's crossover, and the consequences of that realization were so huge that everyone literally died because of it and Barry had to run back in time to prevent it from happening. Plus, Oliver then decided to keep his son a secret from Felicity, leading to some of their biggest relationship issues yet. But the surprise twist that Oliver's late mother paid off the mother of his child to lie and say she lost the baby that resulted from their affair was one of the biggest shocks to come out of a crossover yet. Will "Elseworlds" be able to top this? 

The "Elseworlds" three-episode crossover event begins with an episode of The Flash on Sunday, Dec. 9, at 8 p.m., continuing with Arrow on Monday, Dec. 10, at 8 p.m. and concluding with Supergirl on Tuesday, Dec. 11, at 8 p.m., with The Flash and Supergirl swapping nights for one time only.