Triumph
Charcoal The Burning Man.
Mystek
Monarch
The X-Ternals.
Superboy
Honorable mention Wally West and his family.
In short, if you are created by Priest you are fucked.
The character Triumph (real name: William MacIntyre, sometimes spelled William McIntyre) was portrayed as a hot-headed, arrogant, and self-righteous individual who felt he was "denied his destiny" to become one of Earth's greatest heroes. Via a retcon in a three part story running through Justice League America #92, Justice League Task Force #16, and Justice League International (Vol. 2) #68, he was revealed to have been the founding member of the Justice League, serving as their leader. On his first mission with the fledgling Justice League, Triumph seemingly "saved the world", but was teleported into a dimensional limbo that also affected the timestream, resulting in no one having any memory of him and his original peers now being veterans.
DC Comics fans initially disliked the character; Christopher Priest and editor Brian Augustyn decided to play to this by having the characters dislike him as well.
Charcoal The Burning Man.
Charcoal was created to be a villain, by means of a Wizard magazine contest. However, Wizard Entertainment failed to establish certain legal specifics in the language of their contest rules, leaving the ownership of the character's copyright in question (Normally in such a situation, steps would be taken to ensure that, unless otherwise stated, such a character's copyright would legally belong to the comic's publisher). Furthermore, Wizard Entertainment reportedly failed to provide the contest winner with other prizes promised along with the winning character's appearance in a Marvel comic. Feeling undercompensated, Charcoal's creator attempted to legally claim the copyright for the character from Marvel. Meanwhile, writer Fabian Nicieza had decided to kill off Charcoal and resurrect him later on; because of the legal issues, Marvel told Nicieza it "wasn't worth" bringing the character back.[1][2]
Mystek
While she accepted his offer, her tenure was brief. Soon after joining them, the team was on a mission to the planet Xanthcar, where another member of the JLTF was being put on trial. The cramped space-fairing pod proved to be too much for the extremely claustrophobic Mystek, and, after over two days of travel, she panicked, blasting her way into open space. She soon suffocated and died.
Mystek's sudden death was actually the result of behind the scenes workings. Created by Christopher Priest to be a creator-owned character starring in her own miniseries, Priest was told to put her in Justice League Task Force to generate hype for her in advance. When the plans for the miniseries fell through, Priest simply killed off the character
Monarch
Armageddon 2001 is generally disliked by readers for what has been described as the dishonesty of its resolution. The frame story had been presented as a mystery - which superhero would go insane, kill all other heroes, and take over the world, and why? - and clues were provided. However, at some point during the crossover the future-culprit's identity was leaked. Captain Atom would be the one who became Monarch. The conclusion of the Annual for Justice League Europe, the final crossover issue before the conclusion of the story, seemed to confirm this leak. Waverider had seen the futures of various Justice League Europe members but had not scanned Captain Atom, who was away at the time. The final panel of the issue showed Waverider about to touch Captain Atom, who had just returned, and a text box stated that the story would be concluded in the second issue of Armageddon 2001.[5]
In response to the leak, the surprise ending was changed at the last minute: Monarch was revealed to be, not Captain Atom, but rather Hawk. The problem with this reveal as many fans pointed is that Waverider had seen Hank Hall fight and die against Monarch[6] and that Dove had allowed him to see so many futures as to conclude "No matter the future they fought him but never became him,[7] making Hank Hall and Dawn Granger the two heroes Monarch could not be. Ironically, they were the only characters shown in this situation, and thus any of the other major characters could have been Monarch without creating a continuity issue.[8]
This revelation was extremely unpopular among both fans and professionals, in part because of the logical flaw mentioned above and the disregard for the clues placed in previous issues. Additionally, it required Hawk to behave in ways that many felt to be out of character. This also made it impossible to continue using either Hawk or Dove as they had in the past and necessitated the cancellation of the Hawk & Dove series. Karl Kesel, the writer of Hawk & Dove, commented that "Hawk and Dove was always a love story. Then one day, Hawk went insane and murdered Dove".[9]
Many years later, the DC Comics editorial staff acknowledged that the ending as published was poorly executed and in the Battle for Blüdhaven (a spinoff miniseries from the larger Infinite Crisis event), retconned Monarch's origin and depicted Captain Atom's transformation into the villain.
A storyline in JSA would later reveal that the ending of Armageddon 2001 had been faked by Mordru. He had created an illusion of Dove being murdered by a future Hawk/Monarch in order to drive the current Hawk insane. He then took control of Hawk and used him to impregnate Dove so she would give birth to a child that would inherit all the powers of the Lords of Chaos and Order. Mordru cast a spell on Dove that kept her in a comatose state for years. She did give birth to a child but before Mordru could possess the child's body it was instead inhabited by a reincarnated Hector Hall who aged the body to adulthood and became the new Doctor Fate. Much later while searching for his wife Lyta, Hector would discover Dove and bring her out of Mordru's spell revealing the truth of these events. She would then discover that her sister had inherited the Hawk powers after the death of Hank Hall.
The X-Ternals.
All of the Externals were originally portrayed as immortal and important, playing an extremely major role in the future and Apocalypse's rise to power (as expressed by Cable), but eventually most were killed off.
Rumor says that due to similarities with the Highlander films (with Christopher Lambert) and the following TV series, Marvel was in danger of being sued. That is why they so quickly killed the whole plot. The only Externals allowed to live on were Selene, Apocalypse and Cannonball; since then two of them have been retconned into not being Externals and all three were already well-defined characters before the Externals storyline and did not take part in the gatherings anyway.
Superboy
They haven't come out and said it but they were going through some serious legal stuff over the Superman brand and they needed a big death for Final Crisis. So they killed two flamebirds with one stone. He got better though.
Honorable mention Wally West and his family.
Damn you Johns, damn you to hell.
In short, if you are created by Priest you are fucked.
I don't remember if they used his correct title between IC and Sinestro Corps War, but that's what I was getting at. The same battle caused Superboy's original run to get cancelled years earlier and Smallville to avoid any Superboy references.
