Citations:headcanon

Noun: "(fandom slang) elements and interpretations of a fictional universe accepted by an individual fan, but not found within or supported by the official canon"

 * 2012, Maggie K, "Let's talk about socks: Gender performativity in Terry Pratchett's Monstrous Regiment", Queer Vertigo 2012 (University of Technology, Sydney), unknown date, page 17:
 * Technically, the social context of Borogravia is such that the actual external difference between a trans man and a woman disguised as a man is practically indiscernible – the technology level means they’re indistinguishable by the bodily modification standard (although now that I think about it, there's no reason Igors couldn't perform sex changes, and that's going in my headcanon now), and there does not appear to be a space in the language for self-identification.
 * 2012, To-Van Hoang, "Fanfiction writer adds her own style", The Hoofprint (Walnut High School), Volume 44, Issue 6, May 2012, page 13:
 * "Fanfiction expands your knowledge of characters," Lim said. "There's headcanon, but fanfiction allows you to explore little nuances that writers don't have the time for. You can go more in-depth."
 * 2012, Bea Huff, "Love the character, not the actor", Daily Nebraskan (University of Nebraska-Lincoln), Volume 111, Issue 151, 11 June 2012, page 3:
 * That wouldn't be so bad if it weren't for the fact that they just fill in the missing information with whatever headcanon (one's personal belief of what is true to the universe) they want instead of actually trying to find out more about the character.
 * 2012, Daniel Nye Griffiths, "The Real Hero Of Mass Effect Explains How - And Why - The 'Reject Ending' Works", Forbes, 28 June 2012:
 * And there is a degree of speculation necessary which could be waved away as “headcanon”.
 * 2012, Steven Buchele, "'Homestuck' absorbs readers", The Collegian (University of Tulsa), Volume 98, Issue 9, 29 October 2012, page 6:
 * "Players” draw their own conclusions to explain some of the detail in what they are reading, and eventually establish their own “headcanon.”
 * 2013, Kristal Frenero, "Fifty shades of fan crazy", The Talon Newsmagazine (John A. Ferguson Senior High), Volume 10, Issue 2, February 2013, page 8:
 * Don't forget if they can write pages and pages and pages of “headcanon” information for an already developed character, probably changing his or her already set personality or even expanding upon it.
 * 2013, Peter Berg, "Hobbyhorsing", in Anne Jamison, Fic: Why Fanfiction Is Taking Over the World, BenBella Books (2013), ISBN 9781939529190, unnumbered pages:
 * I currently have a document of My Little Pony story ideas that is, at the time of this writing, over 250 pages in length. It consists of over 400 premises for stories categorized with more than thirty-five different color-coded tags, a timelime of events spanning over 400,000 years and fourteen pages, over 49,000 words of headcanon, and forty-one original characters.
 * 2014, Zoe Kilbourn, "PSA, UWU: Tumblr, Gender, and Gaga", Pelican (University of Western Australia), Volume 85, Edition 6, circa September 2014, page 9:
 * Conceptually, linguistically, Tumblr textpost discourse doesn't translate well to outside life - you don't, or at least didn't, win friends with Meyer [sic]-Briggs personality scores, Harry Potter headcanon, or soft grunge.