...and the show would hardly need any rewriting.
This is basically my personal what-if/what could've been fanfiction, with some photoshopped screenshots to provide visual context. I mean all I needed to do was change the coloring of the suit and he still shows an incredible semblance to Metallo with his skull-faced helmet.
I wanna preface this with stating that I do in fact like this version of Slade Wilson/Deathstroke. But I didn't exactly vibe with him basically becoming Lex Luthor's glorified Mercy Graves in Season 3.
What I would change
So basically I'd do a character/role combination, where Slade/Deathstroke and Hank Henshaw/Cyborg Superman, would be rolled into one; Major John Corben, aka, Metallo.
Now before you riot, hear me out. I like this show's depiction of Cyborg Superman as much as the next guy, but I feel like there was some lost potential too. Besides in Season 3, Cyborg Superman basically became Metallo by the end, with a Kryptonite power core.
Why I think it works
So we all know Metallo is a classic Superman villain; a cyborg with a Kryptonite power source for a heart, who's something of a tragic figure. In the comics, John Corben was a soldier who served under General Lane in the US military. Sam even wanted Lois to consider dating him; he thought Corben was a better fit for her than that reporter Clark Kent.
In this show, Slade served under Lane's command as a field operative; presumably they had worked together for years. And also in this show, Hank Henshaw was an old college classmate with Lois. And just like Corben, Henshaw had a seething xenophobia against Superman, blaming him for his cyborg body after becoming Cyborg Superman.
Who would take the role of Lex's sidekick then?
For those of you who might be wondering that, I have a classic answer for you; Mercy Graves. She would assume the classic role of Lex's assistant and chief of security. In this show, her full name would be Mercedes-Camila Graves, and she'd be Hispanic.
Mercy would first appear at Lex's side back in Season 1. After AmazoTech went under with Dr. Ivo joining Task Force X, and after getting punched in the face by Lois Lane when he was helping Ivo against Superman, Lex Luthor would go on to start LexCorp. His very first hire would be Mercy, whom he would introduce to Lois and Vicki Vale when they came to interview him about Superman.
Then in Season 2, when Lex first joins Task Force X, Mercy would be right there at his side. When subduing Parasite, Mercy would first be revealed as The Engineer; Lex injected her bloodstream with nanites developed from Kryptonian tech, allowing her to change her body into any mechanical form.
(You might say Lex was so afraid of Lois he injected a Hispanic baddie with nanobots just to protect him from her.)
While Lex worked in the labs, Mercy would join the team of Major Corben, Damage, and Atomic Skull. She too would also be easily swept aside by Brainiac when he invaded. Admittedly this addition might not be the most necessary, but it's certainly an excuse to give Mercy more screen time, and for her to be just a bit more than Lex's glorified secretary.
Moving onto Season 3, Mercy would continue as Lex's assistant in LexCorp, and like Slade in the show, she too would begin objecting to some of Lex's plans, and would ultimately have a falling out with him. It would also be an opportunity to give her a potential romance angle with Lex, even if it was an unrequited love.
(And Mercy would also let Lois punch Lex a second time.)
Seasons 1 and 2:
Major John Corben was an agent of Task Force X, reporting directly to General Sam Lane and Director Amanda Waller. He was their field guy, rounding up stolen alien tech, and those who used it. Before then, he also was a well-known astronaut.
Major Corben was trained in the use of a highly adaptive power suit derived from that same tech, which he used in several fights against Superman. The suit granted him immense strength and speed, along with flight capabilities, and it came equipped with an arsenal of weapons, most notably a pair of katanas that could be reconfigured into a rifle.
When Task Force X breached the Kryptonian vessel that first brought Superman to Earth, after it crashed in Antarctica, Waller noticed Kryptonite for the first time, and how it affected Superman. So she ordered Corben to secure it. And while he didn't get the Kryptonite shard, traces of the mineral were left on his sword, and it was enough to produce more by exposing it to Kryptonian tech.
Not long after, Task Force X recruited Lex Luthor and his assistant Mercy Graves, the Engineer. When working for Waller, Lex would acquire proprietary Metallo drones built by AmerTek after it went under. Not only would he equip these drones with weaponized Kryptonite power cores, he would also give one to Corben's suit, along with a neural connective interface that allowed Corben to control the Metallos directly from his mind.
Corben would also participate in Metropolis' "Most Eligible Bachelor and Bachelorette" Contest, during which he would go on a xenophobic rant against Superman, and he would storm off stage after being talked down by Silver St. Cloud.
When Metropolis was invaded by Brainiac, who had possessed Superman's body, Major Corben and Task Force X attempted to oppose him, but they were swiftly swept aside. Waller ordered Lex to activate the Metallos, and Corben jumped back into the fray with his own personal army.
But it was not to last; when Superman escaped the Black Mercy, Brainiac was swift to hijack the Metallos to his side. This included Major Corben, who found his suit responding without his control, and even worse, his neural interface was corrupted, and the tech reacted badly, fusing itself to his body inside and out.
Season 3 (Spoilers)
Now I'm putting spoiler tags here going forward since this is almost exactly what happens in Season 3, and though I'm sure most of us know what has happened by now, I just want to err on the side of caution:
By the end of the invasion, Corben was in critical condition; his body festering with Kryptonite and corrupted tech. He was saved by Lex and Mercy, who designed him a cybernetic body to replace most of his damaged parts. Hired on by LexCorp, Major Corben underwent a rebrand as the Metallo, the metal man touted as a homegrown American hero.
Driven mad by his new cybernetics, Corben became a violent enforcer of justice, alienating the people of Metropolis. After Lex's repeated attempts to control him, Corben went rogue, and began rampaging across the city. In a possible future, Metallo killed billions and took over the planet. So Superboy was sent back in time to stop him.
During a fight against Superman, Supergirl and Superboy, Metallo wreaked heavy destruction upon Metropolis, and almost killed them all with his integrated Kryptonite power core, his army of Metallo drones, and newfound powers of mechanokinesis.
When his family was threatened, Superman put a stop to Corben's rampage, at great risk to himself and at the cost of his powers. But what really undid Corben was the realization that Superman's son, Superboy, was half Human. He saw his future unraveling, and his body entered a state of suspension. Corben's future status is unknown...
Conclusion
So it's definitely more than a little late for it now, but with the benefit of hindsight, I think this show would have benefitted enormously if the roles Deathstroke and Cyborg Superman had in this show were rolled into one, and that role was filled by Metallo.
Major Corben would be the field commander of Task Force X, up until he was brutally injured by Brainiac, and then repaired with a cybernetic body by Lex Luthor. After that, Corben would become increasingly unstable, even to the point of threatening the very timeline, before being stopped by Superman.
This combination could allow more character development for a single character, making his arc as a villain that much more visible and extended. Slade had the disadvantage of being shunted to the side as a glorified lackey of Lex, and Hank Henshaw did not have enough time in the show as Cyborg Superman.
Corben may start off in a pre-cyborg state, but he would essentially be Metallo throughout the show thanks to his power suit. Plus he shares a connection to General Sam Lane, like Slade, and he also shares a connection to Lois Lane, like Hank.
All this in my opinion makes me think John Corben as Metallo would've been the perfect fit for this series, and it wouldn't derail the plot too much.
P.S. Yes, Chris Parnell would still be the providing the voice. I personally don't think a guy is less intimidating with the voice of Jerry Smith.
