Dazzler (Alison "Ali" Blaire) is a superheroine appearing in American comic books published by Marvel Comics, often in association with the X-Men. She first appeared in Uncanny X-Men #130 (February 1980).

A mutant with the ability to convert sound vibrations into light and energy beams, Dazzler was developed as a cross-promotional, multi-media creation between Casablanca Records and Marvel Comics until the tie-ins were dropped in 1980. A committee of Marvel staff, principally writer/editor Tom DeFalco and illustrator John Romita Jr., created the character. She starred in a self-titled series in the early 1980s which lasted forty-two issues, a Marvel Graphic Novel titled Dazzler: The Movie, a four-issue limited series co-starring Beast titled Beauty and the Beast, and later joined the cast of Uncanny X-Men. She has also featured in other Marvel teams.

The character is considered a gay icon due to LGBT readers, particularly gay men, enjoying her disco aesthetic, popstar stage persona, and strong-willed characterization.

Halston Sage portrays Dazzler in Dark Phoenix.

Dazzler was conceived in early 1979 as a joint venture between Marvel Comics and Casablanca Records, a subsidiary of Universal Music Group that had achieved considerable success with notable disco acts including Donna Summer and Village People. Accounts differ as to which party made the first move; in 1986 Louise Simonson would tell Amazing Heroes that Casablanca approached Marvel; however, in a 2011 blog post Jim Shooter would credit the idea to Marvel employee Alice Donenfeld and based on the success of The Archies, who later pitched it to Casablanca supremo Neil Bogart. Bogart was enthusiastic, not only wanting to produce music 'by' the character (who initially had the working name of 'Disco Queen') but also launch it with a half-hour animated special featuring numerous Marvel characters. Marvel began shaping the character; Shooter assigned the development to Tom DeFalco (who, like Shooter, had experience working at Archie Comics), Roger Stern, Roberta 'Dickie' Mackenzie and John Romita Jr. while continuing to oversee the project himself. Shooter recalled that DeFalco pitched the name 'Evelyn Free' (a pun on "evil and free") for the character's civilian identity before the group decided on Alison Blaire. At this stage much about the character was in flux; Romita Jr. initially designed her as African American, heavily based on singer/actress Grace Jones with a costume inspired by the skin-tight and revealing eveningwear he had seen on women at New York nightclubs; her name was changed, first to Disco Dazzler and then to simply Dazzler at the suggestion of Stern; and initially her powers were to be an ability to make people tell the truth. DeFalco objected to the latter, feeling it was "not very interesting for a comic book". Instead he successfully suggested that as her name was Dazzler light-based powers made more sense. Casablanca held final approval over the character at this stage, and vetoed some of Marvel's ideas. DeFalco would recall that the numerous delays led the creative team to believe disco "would be dead" before Dazzler's debut as the various parties hammered out the initial story, which DeFalco and Romita turned into an origin story

Meanwhile, the multimedia side of the project changed several times. Shooter had produced a pitch for the TV special that had impressed Bogart so much he wanted to turn it into a live-action special with many stars he had under contract (including Cher, Donna Summer, Kiss, Lenny and Squiggy, Robin Williams and the Village People) to appear as Marvel characters. However, soon afterwards Casablanca struck financial trouble, and Bogart was forced out of the company. Instead filmmaker John Derek showed interest in Dazzler as a potential film vehicle for his wife Bo, who were looking to build on the success of 10 with studio Filmworks. As such the comic character was redesigned to more closely resemble Derek herself, becoming a white blonde, requiring Romita Jr. to redraw the work already done on the comic. The artist was unimpressed with the changes to the lead character. According to DeFalco, the Dereks' involvement in the project ended after the poor reception of their vehicle Tarzan, the Ape Man

Marvel had planned to release the 34-page Dazzler comic as part of the Marvel Comics Super Special series, which generally dealt with media adaptations, while some thought was also given to releasing it as a black-and-white magazine. After Casablanca and Filmworks both withdrew, Marvel shipped the concept around other record labels and film studios without success. While this was happening, Dazzler had appeared in other titles to build anticipation.

The character debuted in Uncanny X-Men #130 (dated February 1980) as an ally of the X-Men, and subsequently guested in issues of Amazing Spider-Man (#203, April 1980) and Fantastic Four (#217, April 1980). Due to the character still being in flux while these issues were produced they featured some inconsistencies - Richard Gagnon of Amazing Heroes noted the character was considerably more streetwise in her X-Men appearance than she would be for most of her subsequent appearances, while in the Spider-Man guest spot Dazzler fired beams from her eyes due to DeFalco having to tell Marv Wolfman to simply take pot luck over which of the three potential variations in powers Casablanca were mulling over at the time would be finalised.