Artemis Crock in the comics is the child of Paula and Lawrence Crock, all three being unrepentant supervillains. In the show Artemis is ashamed of her criminal lineage and Paula does a Heel–Face Turn after being crippled and spending six years in prison.
Cheshire, who is Artemis' sister on the show (but not the comics), is introduced as a villain and member of the League of Shadows, but evolves into an Anti-Villain or Anti-Hero by season two. In the comics she once nuked a country For the Evulz. Her development when it comes to Lian is also better, as she chooses to stay away in order to not be a bad influence for her, panicking when Lian presents a homemade replica of her mask over the phone.
The tie-in comic does this both to Gorilla Grodd and King Nanaue Sha'ark. Both are borderline Token Evil Teammates for their respective groups (Grodd being a member of a group of gorillas given Kobra Venom by the Brain, with the Team helping them rebel against him, and Nanaue Sha'ark being the teenaged king of the Atlantean province of Nanauve and being more brutish towards enemies) but are set up as adversaries of greater villains. Grodd becomes a subversion, however, as he begins showing his true villainous motives by the time the Team meets him again in the captivity of the Collector of Worlds (Grodd uses his telepathy to hide a group of other captive villains from the Team so they leave without finding out), while the grown up King Sha'ark seen in season 4's Atlantis arc remains a straight example who while still brutish, is primarily an ally of Atlantis.
In the comics, Mongul is an Evil Overlord with no real motivation other than being a sadistic bully and general douchebag. In the show, he's still definitely a dick, but his extreme hatred of the Reach and desire to eradicate them makes him a fair bit more sympathetic.
In Superboy comics Dr. Amanda Spence is an Evilutionary Biologist who created Match, and killed Conner's girlfriend Tanya Moon For the Evulz. In the series, Conner accuses her of creating Match but it turns out this is unfounded, and she later helps create the anti-Starro technology.
The Aquaman villain Black Manta is reimagined as a sophisticated and somewhat noble villain who has numerous Pet the Dog moments with his subordinates, particularly his son. In the comics, he's an utterly heartless Sociopath and doesn't give a crap about his son, and even threatened to kill him just to torment Aquaman.
Vandal Savage in the comics is probably the single most thoroughly vile individual in The DCU with many thousands of years worth of absolutely horrific crimes to his name. In the show, he's still definitely not a nice guy, but he's a Knight Templar visionary whose acts are motivated by a desire to drive humanity to advance and make Earth a major universal power. While he does deliver a Neck Snap to one of his own daughters, Olympia, it is a Mercy Kill as she was becoming increasingly senile. His brutality towards the show's version of his daughter Scandal Savage, renamed Cassandra, is given a nod at one point, but it was not enough for her to turn on him, she instead used it as a cover story to become a Fake Defector.
Rumaan Harjavti is depicted as a benevolent figure and the democratically elected president of Qurac. In the comics, he was the Bialyan Queen Bee's predecessor as the ruler of Bialya and like her was a foe of the Justice League, though he was less intelligent, his original villain nature is present in his successor and brother Sumaan.
Major Force is implied to be a subversion. In the comics he's a violently sociopathic and blood-thirsty villain. In the comic tie-in to the show he's a hero sponsored by the government, whom the Justice League want to recruit. The reason he's not on the league is because Captain Atom shoots his suggestion down because of history he has with Force, his dialogue implying that Force isn't as heroic as he seems. Later on, it's confirmed he is indeed evil like in the comics, though only mentioned as having conquered planets offscreen for the Light.
In the comics White Martians are evil with the sole exception of Miss Martian. In this continuity J'onn isn't the last Green Martian and White Martians are actually persecuted.
In the comics, Ma'alefa'ak is considerably more, well, malefic. While still villainous, this version is a Well-Intentioned Extremist who is angry about the persecution of his fellow White Martians, while similarly stirring tensions on New Genesis, and there’s no level he won’t sink to in the name of, as he sees it, leveling the playing field (and while still the Cain in a Cain and Abel dynamic, he is changed from being Martian Manhunter's brother to Miss Martian's brother, being renamed M'comm M'orzz, who named himself after a Martian animal named the ma'alefa'ak in much the same manner that Batman uses the imagery of a bat to strike fear into the hearts of enemies). The comic version was a Green Martian who wiped out the other Green Martiansnote Lost in Imitation note: yes, it was the White Martians in both Justice League and Supergirl (2015), so you can be forgiven for thinking it must be so in the comics, but it’s not. in revenge for being justly punished for using his Psychic Powers for Mind Rape of J'onn's wife (though it would later be revealed that he was loyal to Darkseid, similar to the show's portrayal, and that he was probing for the Anti-Life Equation). This slowly begins to be subverted when the season 4 premiere episodes show him accepting a gene bomb from DeSaad, the right hand man of Darkseid, attempting the genocide his comics counterpart was more successful at if it wasn't for the bomb being found and destroyed, though said destruction took a Heroic Sacrifice from Conner Kent when he was going to get married, and thus earned the revolutionist his heartbroken sister's (who Conner was engaged to) wrath. It fully becomes the opposite trope showing shades of being a Not-So-Well-Intentioned Extremist upon his more open alliance with Darkseid in the second half of season 4, followed by aligning with Lor-Zod and then General Zod.
The Young Justice incarnation of Terra goes one further than her Teen Titans counterpart did as the heroes learned early on that Deathstroke was manipulating her and decided to let her make her own decisions while treating her nicely. She ends up turning to the side of angels on her own and becomes a member of the Outsiders in the end, never getting the Redemption Equals Death, er, petrification, of her Teen Titans counterpart, though her brother Geo-Force does a Face–Heel Turn in her place, being Locked Out of the Loop of her actions.
The canon audio play that took place at DC FanDome revealed that Clayface reformed and joined Bowhunter Security. Clayface had a similar redemption arc in DC Rebirth, but the comics used Basil Karlo, and what defines it as this trope is the show's incarnation being Matt Hagen, who had no such arc, instead. When Superman discussed possible new members for the Justice League in "Beyond The Grip Of The Gods", Clayface was one such candidate shown as a result of his redemption.
Livewire started off as a villain as shown in Superman: The Animated Series, often committing crimes willingly, but upon becoming a Canon Immigrant to the mainline comics has occasionally pulled a Heel–Face Turn. The show's younger portrayal of Livewire was a trafficked teenager who only reluctantly did crime, until apprehended by Nightwing's team, which freed her from being controlled and allowed her to make later appearances fully reformed at the Metahuman Youth Center. This takes an extra step in season 4 when she was shown to have joined The Outsiders in the one year Time Skip.
Windfall in the comics was originally introduced as a member of the supervillain team the Masters of Disaster, enemies of the Outsiders, before turning against them and becoming an Outsider herself, though she later turned back to crime when she went on to work for Kobra. When she appeared in the show, she was shown to be a former trafficked metahuman residing at the Metahuman Youth Center, with no mention of any criminal past, her only threat being her difficulty controlling her powers, which she is eventually able to fix by the season 3 finale. By season 4, she then is shown to have joined the Outsiders in the one year time skip, and even attacks Kobra in a flashback.
Both incarnations of Mist were the Arch-Enemy of incarnations of Starman, though the second incarnation, Nash Nimbus, was more sympathetic in spite of taking part in a plot to destroy Opal City. In the show, Mist (her name changed to Andie Murphy) was in a similar boat to Livewire as a trafficked metahuman teenager who was also reluctantly a criminal, before Nightwing's team apprehended her and sent her to the Metahuman Youth Center where she could reform. A small cameo helping Tigress and Halo confirms she joined the Team between seasons 3 and 4.
