Born in Bavaria to the blue-skinned shapeshifting mutant later known as Mystique, Kurt Wagner was shunned at birth due to his having blue skin, pointed ears, fangs, and a long pointed tail. At the time disguised as the Baroness Wagner, Mystique's true identity was revealed after she gave birth to Kurt, and the pair were chased by an angry mob. Fleeing to the nearby falls, Mystique threw the infant Kurt over the edge and fled. Kurt was saved by his natural father, the enigmatic being known as Azazel, and given into the care of Margali Szardos, a sorceress and gypsy queen.
Margali took baby Kurt to the small Bavarian circus where she worked as a fortune teller as a cover for her activities as a sorceress. Kurt was never legally adopted by anyone, but was raised by all the members of the circus, who had no prejudices against "freaks". Kurt grew up happily in the circus with his two closest friends, Margali's natural children Stefan and Jimaine. Stefan feared that his magical heritage may one day corrupt him, and so he had Kurt promise that if he ever killed without reason for Kurt to stop him. During his formative years Kurt exhibited tremendous natural agility, and quickly became the circus's star acrobat and trapeze artist with audiences assuming that he was simply a normal human dressed in a demon costume. Kurt worked closely with Jimaine, and the pair soon became involved in a romantic relationship.
Years later, the Texas millionaire Amos Jardine, who ran a large circus based in Florida, heard of the circus Kurt worked for and bought it. Jardine intended to move its best acts into his American circus. However, he demanded that Kurt be placed in the circus's freak show, where he was imprisoned against his will and drugged in order to remain complacent. Eventually, a young boy would free Nightcrawler, who would threaten Jardine in order to make him remain a better owner to his circus friends. Nightcrawler then ran away and made his way back to Germany where he discovered that Stefan had gone mad and had brutally slain several members of a lost race of half-human creatures. Kurt found Stefan and fought him, hoping to stop his rampage, but in the course of the struggle Kurt unintentionally broke Stefan's neck. The villagers of the nearby town of Winzeldorf discovered Kurt and assumed him to be a demon who was responsible for the killings. They cornered Kurt in the town and were about to kill him when they were all psionically paralyzed by Professor Charles Xavier, who had come to recruit Kurt into his team of mutant super-heroes known as the X-Men.
Kurt agreed to join the group, but before they left for America, he and Xavier went to the Bavarian circus so that Kurt could explain to Margali about Stefan's death. However, Margali was not there, and for years she held Kurt responsible for murdering Stefan. Later, she learned the truth and she and Kurt were reconciled. Kurt was also happily reunited with Jimaine, who had been living in the United States under the assumed name of Amanda Sefton.
After many adventures with the X-Men, including a clash with the Brotherhood of Evil Mutants during which Kurt first met his mother Mystique (although he didn't know it at the time), discovering his ability to be invisible in shadow, traveling through dimensions with Kitty Pryde's dragon Lockheed, and more, Kurt was finally severely wounded during the attack on the underground colony of mutants known as the Morlocks by Riptide, a member of a team of mutant assassins named the Marauders. Kurt was taken to the mutant research facility on Muir Island off the coast of Scotland where he recuperated, but discovered that he could no longer teleport as he originally could, and that teleporting others caused a great strain. After hearing of the apparent "death" of the X-Men in Dallas when the team fought the Adversary, Kurt, Pryde, Rachel Summers, Captain Britain, and Meggan became the founding members of the British super-team Excalibur.
After an encounter with the monarch of Latveria, the armored despot Dr. Doom, Kurt's powers were fully restored after Doom used an electromagnetic scrambler in an attempt to disrupt Kurt's teleportating abilities which instead accidentally realigned them.
Following a misunderstanding with Captain Britain over his relationship with Meggan that resulted in a broken leg, Kurt reformed the team of alien bounty hunters known as the Technet into a team of costumed superhuman adventurers dubbed the N-Men. Following the Technet's departure, Kurt became Excalibur's leader after the team gained several new members, including the alien Shi'ar named Cerise. Kurt helped Cerise become accustomed to her new life on Earth, which led to the pair forming a romantic relationship. This was to be short-lived, however, after Cerise was found guilty of war crimes and returned to the Shi'ar Empire.
After Captain Britain and Meggan were married, Kurt along with Shadowcat and Colossus decided it was time to return to the X-Men. Kurt once more served as a dedicated member of the team until after the battle with the mutant despot Apocalypse that resulted in the seemed death of the first X-Man, Cyclops. Soon after, the ever-devout catholic Kurt left the team to pursue aspirations of becoming a priest. During his studies, Kurt was attacked and wounded by Rax, the hunter of the group of evolved mutants known as the Neo. Fleeing, Kurt encountered mutant doctor Cecilia Reyes, and together the two faced the Neo until the X-Men arrived to swing the tide of battle.
Kurt subsequently rejoined the X-Men while continuing his priesthood studies, but soon after took a leave of absence to mourn the death of his friend and team mate, Colossus. When he returned to the X-Men, it was as a fully ordained priest after apparently undertaking a ceremony at St. Michael's Church in Brooklyn which was overseen by Kurt's mentor, Father Whitney. Kurt even took to wearing a priest's collar as part of his X-Men uniform.
Feeling uncomfortable after his longstanding Catholic training as a result of Kurt's feelings of unrest due to molestations by Catholic leaders, which were only exacerbated after the mutant ex-prostitute Stacy X joined the team and made advances towards him which he could not reciprocate due to his vocation. Ultimately it came to light that Kurt had never been fully ordained, rather he had been telepathically coerced into believing so as part of a plan by the Church of Humanity's Supreme Pontiff to bring down the Catholic Church by installing Kurt as the next Pope then revealing to the world that he was "satan". The X-Men subsequently defeated the Church of Humanity and prevented their plan for world domination.
Soon after, Kurt found himself unable to resist the compulsion to travel to the Isla des Demonas off the coast of Florida. There, Kurt was manipulated into a ceremony with other teleporters like himself that opened a dimensional portal through which came an army of mutant demons. The X-Men arrived to recover their teammate and clashed with the army. During the battle, Kurt was forcibly removed from the ceremony which collapsed the portal, trapping all present into the other dimension. There, Kurt learned that the leader of the army, Azazel, was his natural father and the father of the other teleporters present. A mutant from biblical times, Azazel sought to use his children's combined powers to return to Earth and enslave humanity. However, Kurt rejected him and, with the aid of his newly-found half-brothers Abyss and Kiwi Black, Azazel was defeated.
Nightcrawler has since gone on several missions of an occult nature, culminating in a battle against the demonic Hive who was revealed to be responsible for Stefan's rampage. Nightcrawler would be visited by Mephisto on his birthday shortly after that event, who told Nightcrawler that a war was brewing, and if Nightcrawler would take Mephisto's side, he could have any reward he wanted. Kurt rejected the offer, however. Recently, Nightcrawler has also met the dimensionally-stranded Nocturne, daughter of a Nightcrawler from an alternate timeline, who has taken to calling him "dad."
Recently, Nightcrawler died while trying to save Hope (Hope Summers), the Messiah child, from the anti-mutant villain Bastion.