Harley Quinn First Appearance: The Batman Adventures #12 and How to Identify It

Harley Quinn first appeared in The Batman Adventures #12 (cover date September 1993), published by DC. The source puts it this way: "The Batman Adventures #12 (September 1993, non-canon)".

• She appears on the cover, not just inside: in comics, this was Batman Adventures #12 from 1993 — based on the animated series and retitled Batgirl Adventures for this issue — and she is even featured on the cover.
• Distinguishing from her first canonical DC-continuity comic appearance: her first appearance in mainstream (canonical) DC comics continuity is a separate, later issue, Batman: Harley Quinn #1 (October 1999).

Several later editions reproduce this issue. They are easy to mistake for the original at a glance:

• DC Facsimile Edition: Re-released by DC decades later as part of its Facsimile Edition line, with its own separate on-sale date distinct from the 1993 original printing.

• 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.