The superheroes of The Flash, Arrow, Supergirl and DC's Legends of Tomorrow couldn't fight their evil Nazi doppelgangers from Earth-X without there being casualties. It would certainly be expected that a full-on invasion of Earth-1 by Nazis would result in lots of deaths, but some fans were understandably shocked at how bloody Crisis On Earth-X actually was.The four-hour Arrowverse crossover event saw Earth-1's Central City under attack by the Earth-X Nazi Schutzstaffel. In the final battle, numerous innocent citizens and Central City Police officers in the Nazis' path were cut down before the superheroes arrived to do battle. There was also no sparing the lives of Nazi soldiers throughout the crossover. Plenty of Nazis were killed by the heroes in the course of several eye-popping super fights between the heroes and villains. Even the wedding of Barry Allen (Grant Gustin) and Iris West (Candice Patton) was interrupted by their priest being killed when the Nazis invaded the church.

Here are the major characters, a few of whom were big surprises, who lost their lives in Crisis On Earth-X:

Earth-X's James Olsen

The first casualty of the crossover was the James Olsen (Mehcad Brooks) of Earth-X. In the guise of the Guardian (with a shield adorned with the stars and stripes of the flag of the defunct USA), James failed to stop the Oliver Queen of Earth-X (Stephen Amell) from taking the dimensional transporter of the Freedom Fighters. After a brief fight, Oliver murdered James before securing the transporter, not fearing James' dying promise that there were others like him who would try to stop him.

Earth-X's Tommy Merlyn

Wearing the hood of Prometheus, Tommy Merlyn (Colin Donnell) was captured at Barry and Iris' wedding after being taken down by Sara Lance (Caity Lotz) and Alex Danvers (Chyler Leigh). Tommy was imprisoned in the Pipeline beneath STAR Labs and offered Earth-1's Oliver some background on what life is like on Earth-X before he committed suicide via cyanide.

Earth-1's Tommy was Oliver's best friend and the same held true for Oliver and Tommy on Earth-X. Tommy was Arrow's first major death when Tommy died during the Undertaking in the season 1 finale. Tommy briefly reappeared as a vision in the 100th episode of Arrow during last year's Invasion crossover. With Tommy unexpectedly returning once more in Crisis on Earth-X, it's now becoming a fun tradition for Colin Donnell to reappear during the annual Arrowverse crossovers.

Earth-X's Red Tornado

The Earth-X Freedom Fighters had a Red Tornado android of their own, which they deployed to destroy the interdimensional gateway to Earth-1. The Flash and the Ray (Russell Tovey) raced to stop the Tornado, as their own teammates were still fighting to secure the gateway from the Nazis. Together, Flash and Ray managed to destroy the Red Tornado by combining their powers into a lightning bolt attack.

Supergirl (Melissa Benoist) fought a rogue Red Tornado in season 1 of her titular series, but the Earth-X version looked to be a much more sophisticated and improved design than the one the Girl of Steel ultimately destroyed.

Earth-X's Metallo

The Schutzstaffel deployed their own Metallo when the heroes were beaten by Overgirl, the Dark Flash (Tom Cavanagh) and the Nazis at the end of the second hour. Metallo's Kryptonite heart and energy blasts prevented Supergirl from escaping STAR Labs when Iris West and Felicity Smoak (Emily Bett Rickards) tried to rescue her. In the end, the combined powers of Cisco Ramon (Carlos Valdes), Black Canary (Juliana Harkavy), Firestorm (Franz Drameh), Team Arrow and the Legends of Tomorrow overwhelmed and destroyed Metallo.

Supergirl and her cousin Superman (Tyler Hoechlin) faced two Metallos in season 2 of Supergirl, needing the help of the Martian Manhunter (David Harewood) and Alex Danvers to ultimately prevail. The Earth-X version of Metallo is a robot, compared to the cyborg Metallos found on Earth-38, but was no less equipped with a Kryptonite heart.

Earth-X Gideon

Earth-X had their own Waverider timeship, the Wellenreiter. Its artificial intelligence Gideon was voiced by Susannah Thompson, who portrayed the Queen matriarch Moira Queen in the first two seasons of Arrow. Like Colin Donnell, Thompson reprised her role in the 100th episode of Arrow. This year, she returned as the voice of her Nazi son's A.I.

The Wellenreiter, and Earth-X's Gideon along with it, was destroyed by the Waverider piloted by Harrison Wells, Iris West and Cisco Ramon after Killer Frost (Danielle Panabaker), Vixen (Maisie Richardson-Sellers) and Zari Tomaz (Tala Ashe) lowered the Wellenreiter's shields.

Overgirl

Overgirl was the reason why the Nazis invaded Earth-X. The Nazi Kara Zor-El doppelganger was dying from red solar radiation exposure and needed a heart transplant from Earth-38's Supergirl. Overgirl was a General in the S.S. and the wife of the Nazi Führer Oliver Queen. Together with the Dark Flash, the Eobard Thawne of Earth-1, they were the triumvirate in command of the Schutzstaffel and the rulers of Earth-X.

Suffering from the debilitating effects of her illness, Overgirl desperately needed Supergirl's heart, but was denied when the Legends of Tomorrow successfully freed Team Arrow, Team Flash, and Supergirl from captivity in STAR Labs. The Nazis launched their final assault on Central City when Earth-1's Oliver rejected Oliver-X's demand that they hand over Supergirl in exchange for a full retreat to Earth-X. Overgirl was in command of the Wellenreiter during the attack before Supergirl challenged her. During their final battle, Overgirl began to overload, but Supergirl managed to fly her into space to save Central City below before Overgirl finally exploded in a solar flare.

Earth-X's Oliver Queen

Also known as the Dark Arrow, Oliver rose to become the Führer of the New Reich on Earth-X. The loving husband of Overgirl, Oliver-X's entire invasion of Earth-1 was ostensibly to bring another Earth under the control of the New Reich but his true goal was much more personal: to save his wife's life by kidnapping Supergirl so that Overgirl could have her heart. After learning of the existence of multiple Earths from Eobard Thawne, Oliver-X secured the Freedom Fighters' dimensional gateway so that he could breach to Earth-1 and capture Supergirl.

Earth-X's Oliver Queen did not have the relationship with Earth-X's Felicity Smoak his doppelganger has, but he was friends his Earth's Tommy Oliver. During the battle for Central City, the two Oliver Queens fought to the death. When Overgirl exploded in the sky and died, Dark Arrow was so distracted and distraught, he turned his back on the Green Arrow. Earth-1's Oliver shot Oliver-X in the chest with an arrow, killing the Führer.

Martin Stein

The most tragic death of Crisis in Earth-X was Martin Stein (Victor Garber), the senior half of Firestorm and founding member of the Legends of Tomorrow. Kidnapped to Earth-X along with Jax, Green Arrow, the Flash, White Canary, and Alex Danvers, Stein was shot multiple times by S.S. soldiers. while heroically activating the dimensional breach back to Earth-1. Stein died on board the Waverider when he asked Jax to sever their psychic link, which was the only thing keeping Martin alive, but was also killing Jax. Martin was buried in Central City among his friends and family, including his wife Clarissa (Isabella Hoffman) and daughter Lily (Christina Brucato), whom he was planning to come home to after he could separate himself from the Firestorm Matrix and retire from the Legends.

Garber was planning to exit Legends of Tomorrow so he could return to Broadway. Fans had speculated how Martin Stein would be written off the show. With a multi-episode arc about how Jax and Stein could separate from Firestorm and the tease that STAR Labs had developed a Firestorm cure at the start of the crossover, fans were lulled into a belief that Stein would be able to return home to his family as he hoped. Stein's death was quite a shock and a truly emotional blow.

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The epic scale of this year's Arrowverse crossover certainly had a worthy body count. Of course, in the Arrowverse, death has often proved to not be a permanent condition. With time travel shenanigans (the Earth-Xers had their own timeship, after all), 48 more Earths in the Multiverse, and numerous other comic booky gimmicks to employ, anyone who died in Crisis On Earth-X could be resurrected in the future (or from the past).

Which dead character from Crisis On Earth-X do you want to see come back to the Arrowverse? Let us know in the comments.

NEXT: HOW THE NAZIS CONQUERED EARTH-X