The German born Nightcrawler made his first appearance in Giant Size X-Men #1, released in 1975.

The first of Charles Xavier’s all new team, Kurt Wagner came to the X-Men complete with codename and costume, both formerly used during his life as a circus performer.
The character was created sometime earlier however, and was not originally intended for the X-Men. In fact, he was first offered to Marvel’s ‘distinguished competition’, DC Comics, for their Legion Of Superheroes offshoot, The Outsiders, but was deemed “too funny looking” by DC’s editor Murray Boltinoff.

Created primarily by artist Dave Cockrum, who had sketched the demonic looking character several years earlier, Nightcrawler ended up in the X-Men when it was decided to include a non-human, almost scary character in the new team line-up. Another of Cockrum’s designs, the bat-winged Vampyre, was also considered, but the entire creative team preferred the blue-furred, barbed-tailed Nightcrawler, and didn’t think there was room for two good-hearted, freaky looking characters, so Vampyre was scraped in favour of Nightcrawler.

Writer Len Wein added the German background, creating his civilian name by combining the names of German (actually Austrian) chancellor, Kurt Waldheim and composer Richard Wagner (Nightcrawler could have easily been Richard Waldheim then…doesn’t have quite the same ring to it though).
Wein and Cockrum argued about his personality however. “My version was very animalistic, howling at the moon and stuff,” says Cockrum. “And I’d just taken a fencing course, so I saw him as a swashbuckler. But Len saw him as a bitter, tragic monster.” (Wizard X-Men Special, 1999).
“Nightcrawler was always heroic,” Says Wein. “But the devil-may-care attitude definitely was added by X-writer Chris Claremont. But I still recognize the character we created in Claremont’s version.” (Wizard X-Men Special, 1999).
Despite the blue fur, the pointed ears and the fangs, Nightcrawler is not an unattractive guy. “Somewhere along the line it was decided that Kurt was this great looking guy who just happens to be covered with blue fur.” Said artist, Joe Madureira, when he was working on the design for Nightcrawler’s Age Of Apocalypse look. (X-Men Collectors’ Preview, 1995).
Kurt has always been one of the most popular X-Men. Though he can’t claim to have the fan following of Wolverine, he is far more popular than Storm or Rogue. A
Perhaps history would repeat itself…
When X2 was released it was met with rave reviews from fans and critics alike, many singling out Alan Cumming’s as the stand out performance of the film, and that the character of Nightcrawler all but stole the show, including many in the comicbook industry:

From X-Fan
X-FAN: Who was the standout actor for you?
Mike Marts (Senior X-Men Editor): "A toss-up between Hugh Jackman and Alan Cumming. Jackman was great as Wolverine once again, but Cumming did a great job of properly portraying Nightcrawler as a three-dimensional character. Rebecca Romijn-Stamos was better this time around, too."
Dave Cockrum (veteran X-Men artist): "Alan Cumming was the standout, naturally. I thought Nightcrawler - even if he wasn't quite my Nightcrawler - stole the movie."
Jim Krueger (Paradise X co-writer): "I want to say Jackman, but I think Alan Cumming's Nightcrawler stole the movie."
Christina Weir (New Mutants co-writer): "Alan Cumming. I LOVED him. Nightcrawler was the coolest thing in the world. He was amazing to watch visually and then so endearing in his scenes with Storm and Jean."
Darick Robertson (Wolverine artist): "Everyone was excellent, but I have to say Alan Cumming's Nightcrawler was the standout. He really nailed the character."
Such praise has made the decision to omit the character from the upcoming X-Men 3: The Last Stand somewhat bewildering…