In the Static Shock/Superman: The Animated Seriescrossover episode "Toys in the Hood", despite Superman helping Toyman's robot girlfriend hide from Toyman, after her self-destruct sequence is initiated by Toyman (after she betrays both Superman and him), Superman shows no concern whatsoever about her death. This is jarring, considering how far Superman will go to save even Lex Luthor. He'll grieve if he thinks Lex is dying, is a very strict vegetarian in several incarnations, and indeed was hesitant to kill Xenomorphs in a crossover with Aliens! He's frequently had a double standard with regard to non-biological life, though. See his lack of concern for the Bizarros.
This is also pretty bad compared to the Superman episode where the robot girlfriend is introduced. The Toyman doesn't want to take over the world or destroy Metropolis; he just wants to get his property and get out. However Superman treats her like a human being, going to the Toyman's lair to rescue her. By the time he catches up to her and teams up with Static though, she's just a robot.
On the other hand, the DCAU Superman presents every once in a while that he has no problem being a Jerkass when he feels he needs to be. Like the Parasite episodes...He doesn't get any in Justice League, but he makes up for it in Unlimited.
It's not that he doesn't care about Bizarro. Bizarro's too misguided to cause anything but harm on his own and is easily manipulated, so it's best to keep him away from Earth. And Bizarro was shown to be perfectly happy on his planet. He had a carefully built (for him, anyways) rock Metropolis filled with rock people he interacted with, and when he wanted to be a hero, he rolled a boulder at them so he could stop it. And after a hard day of protecting the rock people of Rocktropolis, he went to his "Cave of Alone-ness" to watch his rock TV with rock Lois on his rock couch. Oh, and play with his vicious alien creature... er, "cute doggy" Krypto.
Uncomfortably used in Justice League, in which half of the League itself isn't human and, thus, probably ought to have given this issue more thought. Robots and Always Chaotic Evil gooey white aliens are destroyed without anyone blinking, no matter what they look like, and the latter can be painfully fried out of a human form. Giant monsters and things with too many tentacles get slaughtered easily. The Parademons in the Grand Finale receive Demonic Invaders status honorary of their name and are mercilessly mown down in large numbers. However, directly killing any normal humans, human-like aliens, or alternate dimension duplicates is unacceptable, no matter how insane, murderous, violent, or dangerous the individual has demonstrated themselves to be. Violating Lex Luthor's Joker Immunity quickly sends an Alternate Universe Superman Jumping Off the Slippery Slope, making him a Knight Templar with the goal of stopping crime no matter the means.
Said White Aliens are the reason there is only one Green Martian left.
This is mentioned somewhat in one episode in which Martian Manhunter admonishes Wonder Woman for being too aggressive lately. He brings up an incident against alien invaders, and Wonder Woman angrily replies that they weren't innocent — they thought that humans were food.
In "Growing Pains", Robin befriends a lost, amnesiac little girl who he names "Annie". The child turns out to be a portion of Clayface that has gained sentience and an identity of its own, and in the end is re-absorbed into the main body of the villain, effectively "killing" the girl as a separate person. Robin reacts as if she were always a separate being:
Police Officer: We'll book him on the robberies and B & E, right? Anything else? Robin: Yeah — murder.
Clayface himself ends up on the receiving end in the Justice League episode "Secret Society". While all the other villains are subdued non-lethally as usual, Flash and Hawkgirl cheerfully stuff him in a fireworks cannon and blow him to bits. The scene is treated like a joke, but this was his last DCAU appearance.
In "Chemistry", Bruce Wayne is briefly engaged to a woman who turns out to be a plant clone created by Poison Ivy who he has a very emotional romance with. Bruce and many other wealthy people had been subdued by their new wedding partners through the effect of pheromones and the like. However, once it was revealed that these people — who behaved like thinking, feeling, speaking creatures — were not human, Batman and Robin killed them all, Robin at one point melting one with a gleeful smile on his face. Sure, they were evil, but if they'd been human con artists, the story would not have ended that way.
In "His Silicon Soul", Batman encounters his robot double created by a supercomputer that decided to replace all people with machines to its ends but he turned out to be a copy so perfect that he even has his Thou Shalt Not Kill rule. Batman is able to deduce this and when cyber-Bats thinks that he has killed him, the shock causes the android to turn against his master (Batman's plan) and destroy it at the cost of his own "life". Afterward, Batman commented that robot's sacrifice means he could actually have had a soul:
Alfred: It would appear, sir, that it would prefer to sacrifice itself rather than allow innocent lives to come to harm. Somewhat like you. Batman: It seems it was more than wires and microchips after all. Could it be it had a soul, Alfred? A soul of silicon, but a soul nonetheless?
In a few episode commentaries (e.g., "Heart of Steel, Part 2" and "Read My Lips"), the creators note that the network would let them get away with a lot more graphic violence if the target was nonhuman (e.g., the robots in the former or the Scarface dummy in the latter). They gladly took advantage of the opportunity.
In the aptly namedBatman Beyond episode "Terry's Friend Dates a Robot", a high schooler orders a sentient robotic girlfriend from a roboticist. He specifies that he wants her to love him unconditionally and be 100% (i.e., fanatically) devoted to him. He enjoys the popularity having an attractive girlfriend brings him and begins hitting on other girls right in front of her. This obviously makes her jealous and she becomes possessive of him to the point of attacking people who either threaten him or her claim on him. When he calls her out on this, she pleads with him saying he is the only reason she lives and that she was only doing exactly what he had her programmed to do. He proceeds to break up with her anyway, giving an insincere Let's Just Be Friends speech. She is so angry and heartbroken that she is Driven to Suicide. The show treats this ending as humorous and the main characters share a laugh.
Applied thoughtfully in The Zeta Project. The title character, Zeta, is a robot who gains a conscience and decides not to kill anymore. With time, it becomes evident he's his own person, with opinions, thoughts and knowledge he was never meant to have, and he's learning from the world around him much like a child would. The problem is that the agency that created him doesn't believe that he's sentient now. They think he's been reprogrammed. They treat him like a dangerous weapon. Zeta's friend Ro, however, treats him as a normal human being, since she's realized he's just a sweet, harmless, very, very, very innocent guy.
In the initial arc of Superman: The Animated Series, a bunch of Starfish Aliens stumble upon Brainiac's ship, reactivate him and get swiftly slaughtered for their troubles. Only their silhouettes are visible at that, but their bodily fluids are spattered all over a wall. Nothing even remotely as graphic ever befalls humans. Brainiac himself, by the way, is also fair game for Supes to kill. Then again, this is more because destroying his body doesn't ensure that he's truly dead.
apparently you only count as having a soul if you're good.