One Steve Limit/Western Animation

Inversions of, and exceptions to, a in  include:

"Lash: Friends called me Bat, Bat-Lash. John Stewart: I am John. This is my friend Diana and, er-- Batman (grimly): Bruce."
 * Recess has a Girl Posse of non-identical looking, but identical in personality, rich fourth grade snobs named Ashley, who identify each other by name and last initial. One of the six protagonists is always called by her last name, Spinelli, because her first name is Ashley, and she is as different from the Ashleys as could possibly be.
 * Later episodes reveal the Ashleys all have sisters named Britney Spears in kindergarten and brothers in third grade named Tyler.
 * One episode had Spinelli meet a group of girls who were all named Megan, a deliberate parallel to the Ashleys.
 * Justice League features John Stewart, the Green Lantern, and J'onn J'onzz, the Martian Manhunter. The Flash sometimes refers to them as "The Two Johns." In addition, Closed Captioning for the episodes will sometimes get the names mixed up. Even so, "J'onn" is usually pronounced more like "Jean" while Stewart is often referred to as "Lantern" or "G.L.", to mitigate this.
 * Red Tornado is also John Smith. (Though he rarely goes by this name even off duty.)
 * A minor example, from the Justice League Unlimited episode "The Once and Future Thing" part I:

"Quinn: How would you like it if people called you "White Stormy"? Stormy: [confused] You mean, there's a Black Stormy? Quinn: [looooong pause] No."
 * Ed, Edd 'n' Eddy, after a fashion. Edd is usually addressed as "Double-D".
 * The Oblongs has the Debbies.
 * The Tick (animation) had an episode called "The Tick Versus The Tick", in which The Tick had to fight a guy named Barry, who also used "The Tick" as his superhero name and wasn't keen on sharing.
 * Thomas the Tank Engine/The Railway Series:
 * The Railway Series had a bus named Bertie, and a Small Railway engine named Bert.
 * The TV series had a bus named Bertie, a diesel named Bert, and a Narrow Gauge engine named Bertrum.
 * It also featured tank engines named Bill (introduced in Season 2) and Billy (Season 11).
 * Perhaps the most obvious example of all, Diesel in Duck and the Diesel Engine and Diesel in Stepney the Bluebell Engine.
 * The 1987 Teenage Mutant Ninja Turtles 1987 (or Hero, whatever) cartoon has two characters whose similarity of names can confuse the viewers. There's April's boss named Burne (confused as Verne) and her rival named Vernon.
 * Kim Possible had a student named Ron Reager at the high school. His initial appearance was just for a joke on his sharing a name with Ron Stoppable, but he actually made two more appearances in the Post Script Season!
 * Invoked in another episode, when Dr. Drakken is flabbergasted to learn that the upstart teenager who's always foiling his plans is the daughter of his old college roommate, whose mockery drove him to the evil side of mad science. He tries to claim that he never put it together before because Possible is a very common name, then wanders off to find a phone book when everyone points out that it's really not. The phone book does not help him.
 * The Simpsons has the Ancient Mystic Society of No-Homers; which means only one Homer can join. Unfortunately for Homer Simpson, it's already admitted a Homer Glumplich.
 * The Simpsons is particularly aversive of this trope: Homer and Ned's mothers are both named Mona, Chief Wiggum and Marge's father are both named Clancy, Prof. Frink and the camp accessory salesman from "Homer's Phobia" are both named John, notwithstanding the incredibly similar Carl (of Lenny and Carl) with Karl (Homer's one time secretary); the very closely related Eddie, Edna, and Ned; or Lou, Lewis, and Luann. Plus rhyming names such as Rod, Todd, and Maude; Sherri and Terri or Moe and Joe (Mayor Quimby). Milhouse shared the same name as some random Shelbyville kid ("I thought I was the only one"). And that's not even mentioning Martin Prince or Waylon Smithers, who were named after their fathers (or the prominent first-season character Marvin Monroe, not to be confused with Martin). One particularly elusive one is the presence of two Charleses, one being the minor, bespectacled plant worker "Charlie" and the other being "C. Montgomery Burns", whose real first name is Charles. There's also a gag about two people having the unlikely name of Bort. Of course, this is probably just a side-effect of Loads and Loads of Characters.
 * Chief Wiggum and Ralph Wiggum weren't related by design; they randomly wound up with the same last name, and later, having put two and two together, made them father and son.
 * An accidental reference to this trope appeared in the episode when they go to New York. Homer contacts the traffic authority over the phone and receives a pre-recorded message, with the specific details added in, in a man's voice. The message states that he "will be met by Officer Steve" "Grabowski"—that is, Steve is part of the pre-recorded message, implying that all of the officers are named Steve.
 * Another aversion: In "Waverly Hills 9-0-2-1-D'oh", there are three girls at Waverly Hills Elementary named Caitlin (with a "C"), Katelyn (with a "K"), and Kate Lynn (two words)
 * Yet another aversion: There are two Larrys: the bald guy that isn't Homer who can usually be seen at Moe's, and Mr. Burns's illegitimate son from "Burns, Baby Burns".
 * Sealab 2021 had Debbie and "Black Debbie," who in her first appearance protested her nickname and pointed out the other wasn't called "White Debbie." Some fans call Debbie "White Debbie" for this reason.

""You're gonna need a better Fire Nation cover name. Try Lee. There's a million Lees.""
 * Similarly, Code Monkeys has Black Steve, who was probably called that to differentiate himself from Gameavision's original owner Steve Wozniak, but he continues to be called that even after Wozniak sells the company to Mr. Larrity in the first episode.
 * In later episodes, it serves to remind people who might otherwise try to co-opt his blackness, bitch.
 * Batman the Animated Series, early on, had both Detective Harvey Bullock and District Attorney Harvey Dent. In the first episode, the latter even addressed the former by name (which sounded a little strange)
 * Batman Beyond has two characters named "Ace": The DCAU's version of Ace the Bat-Hound, and the "Ace" member of the Royal Flush Gang (a mute android in Beyond). The two rarely get confused.
 * As is revealed in Justice League Unlimited, The dog was presumably named after her.
 * Trumpton Hugh! Pugh! Barney McGrew!...
 * Winx Club: Pepe, Icy's duck, followed the Trix to Light Haven/Light Rock at the end of season one and hasn't been seen since. The creators must have forgotten about him since in season four, Musa's pet bear was named Pepe.
 * Phineas and Ferb plays this for laughs in the episode "The Lizard Whisperer", where the boys are looking for a giant chameleon named Steve. They find other Steves and even arrive at a Steve Convention. Note the creators are on record as readers of that other Tropes site.
 * There are two girls named Wendy. The first Wendy is the girl Candace competed with in the science fair episode (though her name was never spoken onscreen), and the second Wendy is the girl Baljeet kissed in the Christmas Special. Perhaps for distinguishing reasons, the latter Wendy has the surname Stinglehopper.
 * At several points in the series, Candace mentions wanting to name her future son Xavier, while in "It's About Time!," the tour guide mentions that the time machine was invented by an Xavier Onassis. Of course, this shouldn't be much of an issue, since one's already dead and another isn't even born...until the time-traveling episode "Quantum Boogaloo," where the plot required both to appear. Perhaps to get around this, Onassis shows up without his name ever being mentioned.
 * On a semi-related note, the show introduced Phineas and Ferb's Aunt Tiana around the same time Disney was hyping a different Tiana. Co-creator Dan Povenmire noted the similarity but said it was just a coincidence, as he named the show's Tiana after one of his sisters (the other being the namesake of Linda).
 * For some meta fun, Fanon had declared Baljeet's last name to be Patel, but that's actually the name of his childhood friend Mishti. (His actual last name is Raj.) Also, the character Isabella shares her name with two of the show's voice actresses, and was named after Dan Povenmire's oldest daughter to boot.
 * Obsessive Invader Zim fans will note that the show has a Vortian Lard Nar leading the Resisty and an Irken Lardnar as an Invader. A very minor example, however, since both names are only used in scripts and writers' notes.
 * Enforced on Jimmy Two-Shoes. After The Rodeo Clowns steal one of his shoes, Jimmy notes that without it, he's Jimmy One-Shoe. At that point, a monster dressed exactly like him with only one leg hops by, muttering "And that name is already taken."
 * SpongeBob SquarePants and Squidward once encountered a band of Vikings all named Olaf, except for their leader (Gordan), curiously enough.
 * Avatar: The Last Airbender:
 * "Lee:"
 * Captain Li of the Fire Nation Army.
 * A young boy named "Lei" who Zuko bonds with in his Day in The Limelight.
 * Ty Lee.
 * Li, one of the old ladies who act as adviser for Azula.
 * Quon Lee, imperial guard from finale who had a talk with an engineer in airship.
 * Halfway through season 2, Zuko took on the name "Lee" while incognito, and stopped using the alias once the "Dai Li" (That's pronounced "Die Lee") showed up.
 * And Dai Li is just a different transliteration of the exact same Chinese characters for Ty Lee's name!
 * The whole thing is lampshaded in "Sokka's Master":

""Cosmo! Wanda!" Timmy called, pushing through a crowd of siblings. "What?" asked a boy named Cosmo. "Yes? asked a girl named Wanda. "Never mind," Timmy said, sighing."
 * On a semi-related note, The Dai Li's Government Conspiracy was upheld by placing several women who called themselves "Joo Dee" to watch over suspicious citizens. Justified in this case because they were all brainwashed into the identity anyway.
 * There are two "Estellas" in The Real Adventures of Jonny Quest: Estella Scheele, a one-off antagonist seen in "In the Realm of the Condor," and Estella Velasquez, Jessie's mother. And they're both redheads, too.
 * Kyle in South Park's cousin Kyle, although it seems that instance only exists for the joke that Sheila considers her own son to be "Kyle 2." Other aversions exist through extremely minor characters, such as a second Terrance (who only appeared in the episode right before Terrance and Phillip were introduced) and three recurring Living Props named Kevin, and various stock names used for random characters.
 * There are actually three Scotts: Scott Tenorman, Cartman's enemy and, Scott Malkinson, an unpopular classmate of the boys, and Scott "the Dick", a Canadian seen in "Not Without My Anus," "Christmas in Canada", and "Royal Pudding."
 * Though he's never seen, another Tino is mentioned in The Weekenders when the main character, Tino Tonitini, fails to get his name in the yearbook for "Best Tino". Also averting the "similar names" aspect is minor character Tony Tortallero, who even looks and sounds a lot like Tino.
 * On Hey Arnold!, the title character has a Country Cousin named Arnie who's basically a boring, creepy Bizarro Universe version of him. Obviously the name is part of the joke.
 * One episode has Arnold going through the streets shouting for his lost pig, Abner. A man sticks his head out a window and continually calls "What?!" before giving up and going inside.
 * Related: there's a minor recurring character named Lorenzo and a fictional, plot-significant country called San Lorenzo.
 * Unintentionally done in the Arthur episode "Buster's Back", which includes the titular character and musician Arthur Garfunkel (though in this case, his name is never mentioned).
 * Daria has three Toms: Tom Sloane, who dated Jane and later Daria, as well as Tom Griffin (Sandi's father) and Tommy Sherman (the dead Jerk Jock).
 * There's also two Brians: Brian Taylor, Brittany's little brother, and Brian Danielson, the guy who married Daria's cousin Erin.
 * Invoked in the second episode: Jane tries to get into a party and tells the security guard her name is "Tiffany," figuring that there would be at least one. (Because apparently "Jane" isn't a common enough name?) It turns out there were three, one of whom winds up becoming an important character.
 * In The Fairly OddParents episode "Genie Meanie Minie Mo," Timmy's wish for Trixie Tang to fall in love with him backfires when she ends up giving kisses to everyone in the country whose name is Timmy Turner, with him the very last one on the list.
 * In the storybook Too Many Turners, Timmy wishes that he had lots of brother and sisters, but after he sees how much trouble all those siblings are, he calls out for Cosmo and Wanda to get rid of them, resulting in this scene:

"Frylock: Where is Carl's brain? Carl Brain: I am Carl Brain. Frylock: No, our friend Carl. Carl Brain: I am Carl Brain. Frylock: No, different Carl! Carl Brain: (beat) I am Carl Brain."
 * One episode of Mighty Max has the protagonist, Max(well), compete with another Max(imilian) who might actually be The Chosen One. (Aside from the name, they were born within five minutes of each other.)
 * Aqua Teen Hunger Force:


 * Danny Phantom plays with this a bit with Danny's "Dani-with-an-I" Opposite Gender Clone, Danielle. So, for at least two episodes we had both Daniel "Danny" Phantom and Danielle "Dani" Phantom.
 * Futurama: "Clarification: the Philip J. Fry from planet Earth or the Philip J. Fry from Hovering Squid World 97?"
 * In the Luck of the Fryrish we find out Fry's nephew was named after him and became the first man on Mars, Fry however believes it to be his brother at first to which Hermes says, "Oh, so your brother was that Philip J. Fry?"
 * As Told by Ginger has Macie's parents both named Bobby and Bobbie Lightfoot. Hoodsey's first name is Robert as well.
 * Darkwing Duck has a rather bizarre example with two supervillains both named Negaduck: one the evil half of Darkwing himself the other an Evil Twin.
 * Jimmy Neutron has Jimmy and one of his clones gone rogue, Evil Jimmy.
 * Time Warp Trio had main character Joe and his Uncle Joe, whom gave him the time traveling book the series revolved around. The titular trio (Joe, Sam, and Fred) would also go on to meet their great granddaughters from 2105, whom were named Jodie, Freddi, and Samantha. And that's not getting into the historical figures they'd meet, whom being real life people, also shared a first name with another historical perosn they met while time traveling or a member of the cast.