Who's Black Hand?

Who's This? The guy we can thank for Blackest Night.

The facts: This Green Lantern villain first appeared in Green Lantern vol.2 #29, and I'm not gonna get into it too much because that's the example story below. Apparently, "William Hand" was based on Batman writer Bill Finger. Uhm, okay. I'm guessing Geoff Johns didn't realize this (or care) when he decided to make the character a necrophiliac. He appeared in half a dozen more GL stories in the Silver and Bronze Ages and is enough of a joke by the Bwa-ha-ha JLI era that he gets to appear there, with superhero phobia. There's a bit of a revival around 2005, but nothing major.
How you could have heard of him: Johns made him the herald of the Black Lanterns and the inciting character for Blackest Night (i.e. DC Zombies). Since the New52 didn't reboot Green Lantern, he was still a thing after Flushpoint. Post-Rebirth, he founded a cult called the Dark Church of the Black Hand (eech), and most recently caught the Flash's eye. This is a character who has VERY NEARLY reached Dr. Light levels of objectionability.
Example story: Green Lantern #29 (June 1964) "Half a Green Lantern Is Better Than None!" by John Broome, Gil Kane and Sid Green.

From William Hand's point of view, the story starts in medias res. He's a trenchcoated figure vacuuming Green Lantern residue after the Emerald Gladiator's public appearances.

Whoahhhh there, Gil Kane! What are you doing breaking the fourth wall?! And why are YOU in charge of telling the story when someone else is the writer? What the hell is happening right now?! It gets weirder, because the next 2+ pages has William Hand look beyond the panel wall and TELL US his story, in his own words. Stop acknowledging my presence, noooooooooo!

Ok, so in short. Hand discovered GL leaves radiation when he uses his ring, which is absorbed in nearby objects. Further, that he is motivated by hating his respectable family, so he had to be different and become a crook. He even wrote the book on small-time crime (literally), and has memorized his own words so he can get out of any situation. But I guess he's also a scientist because he was able to build a Lantern energy sucker-upper AND a wand that shoots that energy back at his opponent to push him into another dimension from which Hand will be able to tap directly into the ring's power and make himself the most powerful villain ever (science is wild). Not much of a fashion designer though, or else "Black Hand" might have had more of a hand motif instead of a gray, upside-down triangle... What is that supposed to MEAN?! Other than hands are hard to draw/cut out? Though reportedly drawn to look like Bill Finger, he's not much of a wordsmith either. When your guinea pigs disappear in a flash of green energy, you don't use the expression "vanish into the blue". I'm sorry, that's just how I feel.

It seems he can already tap into the ring though.

Did Black Hand miss the rendezvous? No. This is when that peculiar cover happens. Hand has only managed to shunt HALF of GL into another dimension, and it's NOT the half with the ring. Oops! But the two technologies cancel each other out anyway.

But the power wand is reserved for fighting GL. The rest of the time, Hand uses his photographic memory of his book of crime advice. What does THAT look like? Well...

I'll let you in on a secret. Whatever tricks of the trade I've learned in my life, whatever the trade in question, I just KNOW how to do it. I don't need to write it down then remember it like I'm having a Chuck flash. Weird way to picture this, but hey, maybe Hand isn't neurotypical. I won't hold it against him. Anyway, ½GL comes on the scene and Hand tries to shunt just 1 more % of him into that other dimension so he can "get control". It's a little like shares in a company, I guess.

Later, in nearby Coastville, Hand's three brothers are being honored at a gala, but are surprised to see the black sheep of the family show up in costume, demanding to be honored instead. And if the town refuses, he'll ROB THEM ALL! Yeah, this guy isn't right in the head. Has he thought about running for president? Green Lantern once again tracks him down, and... he is whole! But how?!

Uhm, Silver Age, that's how! Hal learned the whole plot with ring telepathy (which he should use every time, but I bet never does), then "extracted" his reverse image right out of a mirror and stuck onto his right side. It really CAN do anything. And Black Hand just didn't have time to see the "uncanny valley" effect. Finally, the ring just reverses the polarity of the neutron flow on the gadget and voilà! A once-more-complete Hal Jordan delivers Black Hand to justice. Nothing in the book of criminal advice about this, apparently.

To be frank, Black Hand had a boring costume and a confused origin with multiple shticks and, for some reason, pays tribute to Bill Finger (um, okay). It's quite the mess. Making him the king of super-zombies I guess was just another patch in the quilt work.

Who's Next? A quality aviation ace.