In the 1990s, DC decided to make some major changes with their Green Lantern franchise. And with the storyline "Emerald Twilight," they did one of the biggest changes in superhero comics--they turned the series' protagonist, Hal Jordan, into the villain Parallax.
Parallax would play a major role in one of the biggest stories of the 1990s, DC's Zero Hour: Crisis in Time, a story that was meant to smooth out some continuity issues from 1986's Crisis on Infinite Earths. Hal Jordan would be completely transformed both to become a better villain and to suit the needs of that story, even though some of those changes were eventually retconned out when he was re-introduced as the main Green Lantern in the early 2000s.
8 He Became Strong Enough To Beat Any Other Hero
When Hal Jordan gained the power of the Central Power Battery, he became one of the most powerful beings in reality. He was strong enough to literally knock Superman out in a single punch. For a time, this was one of the most iconic panels involving Hal Jordan, as it represented his full turn away from being a hero now that everyone was aware of what he had done. It was this strength that he wanted to use to reset all of space and time, and it took all of the other heroes combined to actually stand a chance of defeating him.
7 Hal Turned Into A Murderer
In the '90s, most heroes operated by the mindset of “heroes don’t kill.” Almost no hero was willing to break it, because that felt like crossing a line that couldn’t be uncrossed. Exceptions were few and far between, as a way to delineate between real heroes and the edgy heroes. So when Hal gave into becoming Parallax, he gave up on the “morals” that were holding him back.
Though he defeated multiple other Green Lanterns while he traveled to Oa, in the end he left them all alive and with enough energy to get somewhere safe. But once he fought Sinestro, the two of them wound up in a knock-down, drag-out fight that ended with Hal killing Sinestro once and for all.
6 He Wanted To Go Beyond Saving The Status Quo
The biggest lesson Hal learned when he broke ties with the Guardians was that it wasn’t enough to be okay with maintaining. By the time he’d truly mastered his powers, he was fed up with that method of doing things. With his cosmic levels of power, his intention was to do more than just be a keeper of the status quo.
Instead, he was going to reset everything and make a perfect universe. He made all sorts of promises that would have led to things like restoring Krypton and more, all because he thought the heroes deserved better than what they got.
5 He Eventually Turned Into The Spectre
After being defeated, Hal hung around for a short while afterwards before finally using his powers to re-ignite the sun. This made up for much of the things he’d done while he was Parallax, but it wasn’t over. Hal was eventually transformed into the Spectre and told that this would be his penance for an untold number of years. This was especially surprising considering that Hal had actually fought the Spectre during Zero Hour, and his victory over him expended enough energy that the other heroes were able to bring him down. Hal remained the Spectre until he was transformed into a Green Lantern once more.
4 He Stopped Listening To The Guardians
Hal had spent years being one of the most loyal fighters the Guardians of the Universe knew. But after years of service, the Guardians wouldn’t grant him the one thing he wanted when Coast City fell.
Worse, they decided to take his powers from him. Enraged, he absorbed the energy from the Guardians’ projection and flew into space to enact his revenge. No longer would Hal be tied down by their esoteric and often outright wrong orders.
3 He Became Willing To Work With Villains
In the end, the true fall of Hal Jordan came not in Green Lantern, but in Zero Hour. Zero Hour saw all of space and time torn apart, with a number of heroes dying as time shifted around them. The heroes believed that the time-traveling villain Extant was responsible, only to eventually learn that it was actually Parallax who was at fault. Hal decided to work with Extant, tapping into his time powers to alter time however he wanted. This was a major part of why everyone was so willing to fight against him, as Extant had shown himself to be a real villain and Hal didn't care.
2 He Became Emotionally Vulnerable
Hal had always been a self-assured guy—and it was his confidence that made him worthy of being chosen as a Green Lantern. But when he decided to become Parallax, fans got to see his vulnerable side. His ring conjured both his parents as well as his first love as he recounted all the mistakes he made. Later, when he met Kyle Rayner, his vulnerability was so great he almost convinced Kyle that he wasn’t evil, only misguided. And he was capable of doing that because even he thought he was just misguided, rather than having acted out of malice.
1 He Wanted To Make Amends For What He'd Done
In the end, Hal recognized that everything he’d been doing was wrong. Initially, he wanted to make things right by taking back his Green Lantern ring and working as a Green Lantern again. Kyle Rayner was even willing to give his ring up to give Hal the second chance he wanted. However, that wasn’t to be. In the end, Hal's desire to do right caused him to use his incredible powers as Parallax to reignite the sun during the "Final Night" storyline, when literally no one else was able to do anything.