While she may prefer to be known as Kate now, for years she was Kitty Pryde, the youngest mutant to join the X-Men and one of the longest-lasting members who has become the personification of Xavier's dreams as the heart of the X-Men.
Of course, while Kitty Pryde exemplifies a lot of the qualities that make her one of Marvel's best mutants, she has had her share of failures, mistakes, and potentially drastic retcons that have also made her the worst mutant in the X-Men's world.
10 BEST: LEADER OF THE X-MEN
As Kitty was one of the first and youngest new recruits to the X-Men, she has spent years training alongside the team and learning from the various mutants that would become her new family, which included time spent with Excalibur in England.
Kitty not only rose through the ranks of the X-Men to become one of the senior members of the team, but she was also left in charge of the school after the death of Wolverine, making her the leader of the X-Men and the shaper of the next generation of mutants.
9 WORST: NEW MUTANT DROPOUT
Of course, Kitty wasn't always the poster-child of the X-Men, and for a brief period of time, she was demoted from the team to the New Mutants due to her youth and inexperience with her abilities, which didn't sit well with Kitty.
After proclaiming that "Professor Xavier is a Jerk!" she begrudgingly spent a small amount of time with the New Mutants before she managed to talk her way back on to the X-Men, which didn't leave the best impression of her on the new class of mutants.
8 BEST: DAYS OF FUTURE PAST
Another Kate Pryde was able to impact the X-Men and the entire course of history in the mainstream timeline during the "Days of Future Past" storyline, though this version was one of the last surviving X-Men from a dark future.
After young Kitty breezed through her first Danger Room training session, her body was taken over by Kate from the future, who helped the X-Men stop an assassination attempt on Senator Robert Kelly that would have led to her dark future. Kate returned to her timeline, though Kitty and the X-Men continue to live in dread of the dark timeline.
7 WORST: LOST HER GRIP ON ILLYANA
While it's not entirely fair to lay the blame for the loss of young Illyana Rasputin/Magik on Kitty Pryde alone, she was the one who lost her grip on the young sister of Colossus during the struggle with the demon Belasco.
This all occurred during one of the X-Men's most dangerous missions when Belasco attempted to free himself from Limbo by kidnapping Kitty Pryde and Illyana. During the X-Men's rescue, Illyana was caught between dimensions so when Kitty lost her grip, Illyana was lost and tortured in Limbo for seven years despite reappearing seconds later.
6 BEST: STOPPED A N'GARAI DEMON
The X-Men discovered an ancient cairn on their property that accessed a dark dimension full of monsters that re-appeared a few times over the years, though in Uncanny X-Men #143, Kitty Pryde was forced to face one of its threats alone.
After the previous destruction of the Cairn, a deadly N'Garai demon was released and began to hunt Kitty Pryde throughout the X-Mansion as the monster tore through after her. Kitty was able to lure the demon into the Blackbird's hangar, where she used the X-Jet's thrusters to incinerate the monster.
5 WORST: LOST CONTROL OF HER MUTANT ABILITIES
Kitty handled herself very well during the "Mutant Massacre" storyline that saw the Marauders decimate the underground society of mutant Morlocks, especially considering she was still a teenager during these dark events.
Unfortunately, Kitty was injured by Harpoon during the battle which caused her to lose control of her mutant phasing abilities, making it hard for her to stay solid. She would have completely lost control and phased away into nothingness if it wasn't for the combined intellect of Doctor Doom and Mister Fantastic.
4 BEST: THE BLACK VORTEX
The Celestial-powered mirror known as the Black Vortex was a powerful artifact that was able to empower people with cosmic abilities, and when it was stolen it brought the X-Men, Guardians of the Galaxy, Nova, and Captain Marvel together.
While a few members of the X-Men and Guardians submitted to its power and gained cosmic abilities to help with the battle, only Kitty agreed to the transformation to help others so that she could use her new abilities to save the planet of Spartax and eradicate the Brood infecting it.
3 WORST: POSSIBLY A NEO
Following Bastion's Sentinel attack on the mutant population during Operation: Zero Tolerance, Kitty, Gambit and Wolverine broke into his systems and activated a series of holographic files that cast doubt on the established origins of a few of the X-Men.
One of the holographic files suggested that Kitty Pryde had been replaced as a baby by the offshoot of mutants known as the Neo, who had recently appeared as powerful enemies of the X-Men. The X-Men decided that the holograms were just Bastion's lies, though the doubt remained in their minds.
2 BEST: BREAKWORLD BULLET
The Breakworld was an alien planet that had received prophecies of their doom that involved the X-Men, which brought them into conflict with the team on Earth that soon brought the Astonishing X-Men to the Breakworld itself.
There they learned of the Breakworld's ultimate plan to destroy Earth using a giant planet-shattering bullet that would destroy everything in its path, including Earth. Kitty merged with the bullet and kept it phased so it harmlessly passed through Earth, though she was lost in the bullet for a while until Magneto was able to rescue her.
1 WORST: DAWN OF X
With the new mutant nation of Krakoa, the X-Men have created a safe place for mutants that is only accessible by mutants, though Kate "Don't call me Kitty" Pryde was unable to pass through the teleporting gates of Krakoa.
There are a number of theories as to why Kate Pryde isn't able to use the gates of Krakoa, which include the controversial holographic file discovered in Bastion's fortress that claimed Kate was actually a Neo instead of a mutant, which could potentially explain why she hasn't been able to be resurrected by the Five on Krakoa as well.