Steppenwolf is technically the first major antagonist in the entire DC Extended Universe, and he kind of ended up being the only one. If we compare him to the Marvel Cinematic Universe, he would technically be its Loki, but there’s not really anyone in the MCU I’d directly compare him to. Despite being played by the amazingly talented Ciarán Hinds, almost everything about this character was handled worse than it should have been.
For one, he doesn’t even have a consistent design. Between different timespans of the film and the different cuts by Joss Whedon and Zack Snyder, Steppenwolf changes quite a bit. That’s somewhat true for Steppenwolf in the comics as well. Like most characters in DC Comics, his design has varied over time, but more than most. I’m not sure if the movie universe clearly established it, but in the comics he’s actually Darkseid’s uncle, even though he still serves under him.
His role and motivations also change between the theatrical release and the Zack Snyder cut. Both versions tie back to Darkseid, but in one he’s trying to redeem himself, while in the other he comes off as more focused on his own goals.
There’s also a big difference in how he dies in each version of the movie. In the theatrical release, his battle is pretty forgettable, and Steppenwolf ends up being defeated in a strange way when the Justice League turns his own Parademons against him. It’s a bit ironic that someone who could take on the entire Justice League is ultimately overwhelmed by what are basically a swarm of oversized insect-like creatures.
In the Snyder Cut, the final battle feels much more epic, and the team effort to bring him down is balanced a lot better. Even his death is somewhat ambiguous in terms of who lands the final blow. Aquaman strikes him with his trident, while the rest of the League contribute before he’s sent through a portal, his dying body delivered back to an enraged Darkseid. It’s a pretty striking moment and almost feels like a symbolic middle finger to what could have been the DC Extended Universe’s Thanos-level villain if the franchise hadn’t fallen apart.