Gambit First Appearance: The Uncanny X-Men #266 and How to Identify It

Gambit first appeared in The Uncanny X-Men #266 (cover date August 1990), published by Marvel, by Chris Claremont, Jim Lee. The source puts it this way: "his first in-story appearance was in The Uncanny X-Men #266 (August 1990), drawn by Mike Collins".

• Competing 'true first appearance' claim (Annual #14): his next chronological story appearance was meant to run in Uncanny X-Men Annual #14 (July 1990), but that issue shipped three weeks early by mistake, ahead of issue #266.
• Depth of Annual #14 appearance (disputes 'cameo' label): in Annual #14 Gambit actually appears across ten pages total, with a full scene introduction, dialogue, and a name reveal, not just a brief cameo.

• Indicia: the small print on the first page or inside cover gives the issue number, date and publisher; reprints usually say so there.
• Cover price and barcode: a price or barcode format that did not exist in the year printed means a later edition.
• Paper and staples: decades-old newsprint is tan at the edges; bright white pages on an old date are a warning sign.
• Restoration: color touch, trimmed edges and married covers are common on expensive keys; a grading service can detect them.

Shoot the front cover flat, straight on, in even light, then the indicia page and the back cover. Include the top edge and staples in one frame. The app reads the title, issue number and cover and matches it against the checks above; the indicia photo settles most reprint questions.