Lex Luthor sold his soul to the devil for regained health.

Long story short: Luthor had cancer because he always kept a piece of Kryptonite on him. He was dying, so he staged his death, then transplanted his brain into a cloned body of himself when he was young and had hair and pretended to be his son, Lex Luthor Jr. But then the clone body grew old and sick super fast because of unstable science or something, so he tried to die in a blaze of glory by taking half of Metropolis with him since he believed half of the city was his, but Superman stopped this and Lex was sent to a hospital where he had to wait for death to eventually end his pain.

Then Neron, DC's version of Mephisto, arrived at his death bed, offering him to turn him into a man in his prime without any sickness at all in return of his soul. Luthor doesn't believe in such things as the devil or the soul, but agreed since he was dying so why the hell not... and became a man in his thirties, healthy and strong. Lex realized that he should have asked for hair as well.

Sinestro became a monster as soon as he got the Green Lantern ring.

Hell, he wasn’t even selected by the ring, it was given to him. Shows us that he was probably never meant to be a GL.

Before he became a GL, Sinestro was an anthropologist who found a wounded and dying Green Lantern named Prohl Gosgotha who gave Sinestro his ring so he could defend himself against the one who was trying to kill Gosgotha. Afterwards, Gosgotha asked for his ring back to keep him alive long enough to get help. But Sinestro knew that it would mean that he would not become a Green Lantern himself, so he watched as Gosgotha died so could keep the ring.

Power corrupts.

Galactus has a daughter.

Yeah, this is a canon thing.

Her name is Gali, AKA Galacta. She has the same powers as the world consumer, but can control her hunger. She uses her powers to protect the planet from threats like alien viruses and living biological weapons by consuming them.

Deadshot started out as a fraud hero.

Believe it or not but the most well-known member of the Suicide Squad’s first costume was a tuxedo and a tophat as he made his debut as Gotham’s new crimefighter, only so he could take over the city’s racket in secret. He was exposed by Batman and swore revenge, becoming the famous hit-man we know today.

Kingpin is a vegan.

Seriously, no kidding. He is.