Creator's Pet: Magog was used constantly to the point of absurdity. By the ending of Geoff Johns' popular run on the book, he was a reasonably popular character (and an homage to DC's legendary book Kingdom Come), but with the new creative team, he became the most important character of the book (despite it having a cast of over twenty characters by this point). Despite fan complaints, Magog soon got centre stage on most of the covers, got to co-lead one entire JSA team on their own book, and even got his own solo series, despite him being a nobody even a couple years before that! The backlash was tremendous, and his hilariously-low-selling book was cancelled quickly, his storyline wrapped up, and the character unceremoniously killed off in Generation Lost by Max Lord, to prevent Magog from creating a future similar to the original story he originated from.
Crazy Awesome: The time Doc Mid-Nite's pet owl Hooty killed a bunch of Nazis while on a drug-fueled rampage (thanks to Hourman's Miraclo pill) when Doc Mid-Nite was down for the count.
Wildcat. Few readers of the forgotten character from the '40s would've expected a Batman ripoff to become a major part of the team, and one of only four Golden Agers left alive.
Many of the original members of the team count as this. Characters like Wildcat, Hourman and Dr. Mid-Nite were also-rans of the 40s, vanishing after a very short time period in the books. Effectively failed concepts, they would have never seen the light again if not for their links to the JSA- so when the JLA/JSA team-ups started happening, out came these obscure failed characters. Fast-forward to modern times, and now many of these originals and successors are now popular heroes in their own rights.
Cyclone is quite popular, what with her ubber woobieness and funny scenes.
Jakeem Thunder is considered this a bit, as he talks in ghetto slang, swears a lot, and acts like a buffoon.
Fans mostly have this reaction to Amazing Man on message boards, not only because of notable suckiness, but because he has so little characterization and moments in the sun, being just a background guy who doesn't say or do anything.
Harsher in Hindsight: Doctor Fate and Alan Scott saying that the legacy of the Justice Society will never be forgotten... Enter the New 52, where the majority of the members don't exist and the Society itself doesn't, and thus has had no influence on the current generation of superheroes.
Ho Yay: There's the almost downright coy bromance between the murderous Black Adam and the (relatively) young and naive Atom-Smasher, who is twice convinced by Adam to abandon the JSA and fight at his side. It makes sense that Atom-Smasher chooses to wear a full-face mask like his godfather Al Pratt: he's hiding the goo-goo eyes he's making at Adam behind it.
Les Yay: Cyclone obsession with best friend and teammate Stargirl frequently leads fans to this trope, but it's never mentioned in-series.
Memetic Mutation: Not much, but because of Alex Ross's...suggestive depiction of Maxine's costume, lead to many making jokes about her apparent lack of underwear or commenting that she forgot it.
Ascended Meme: Which was once noted in story, when a bunch of comments are made about her, from calling her a joke, insulting her former use of wearing a hat, and referring to her as the 'team mascot' or pet, one of the comments heard included 'Does she even wear underwear?' While sorta funny, combined with her face and the other comments, makes it just fuel to her woobieness.
Rescued from the Scrappy Heap: Bill Willingham said this was the goal with Mr. America III, to make something out of a character with so-far zero personality and no powers. He ended up just giving him explosive-tipped whips and a crush on the teenage Lightning (keep in mind that she's a contemporary of Stargirl, while he is likely much older than Atom Smasher, and the JSAers weren't too keen on that relationship. He left the book without doing anything else with him.
The Scrappy: Magog is hated by a lot, partially because he's a massive Jerkass who got a lot of time on screen. A lot of people also cite him hittingMaxine'Cyclone'Hunkel when she was flying overhead because 'she came at him from his blindspot.' Magog has also been accused of being a mouthpiece for writer Bill Willingham's right-wing views.
Shipping: Many fans want to see Captain Marvel hook back up with Stargirl, even badgering the new writers of the book about it. It ain't happening, since they're now handled by two different editorial teams.
Tear Jerker: Three particular incidents stand out—Jakeem Thunder begging the Thunderbolt to bring the dead Johnny Thunder back to life. Stargirl openly weeping over Atom Smasher's dead body (in the process, showing her true feelings for him). And Stargirl's reaction to finding out her hated birth father has died- she breaks down, unable to understand why she cares. "Because you're a wonderful daughter", her stepdad tells her.
Captain Marvel breaking up with Stargirl was easily this especially her pleas for him to tell the JSA his real age and identity and subsequent break down in tears when he leaves.
Cyclone so much! She's been revealed to have no friends, atypical depression, formed a "JSA Fanclub" that everyone bailed on thanks to her motormouth, and has a crush on an older, unavailable Damage. Has settled down now thanks to a friendship with Stargirl.
Stargirl's step-brother Mike, who appears simply so that Stargirl and his dad (STRIPES) can yell at him whenever he brings up how Star Girl stole his birthright to be the next Star Spangled Kid from him.
Power Girl, what with her angst over her convoluted past and the revelation that she's not wanted on the newly reformed Earth-2 since the universe created a new Power Girl to replace her in that world.
Lyta Hall, if you take into account her full past. All the shit she's been through, and then she finally gets her husband back, only for them both to be offed when Spectre goes berserk.