Don't forget Jack The Ripper!
There are oodles of topics that provide plenty of political ammunition, but anybody who takes this one seriously is an idiot.
The phrase you're thinking of is "headcanon" (cf. https://en.wiktionary.org/wiki/canon), although "head cannon" evokes a much funnier mental image.
That's a mystery long solved, friend[0].
One of the best, among many, of the series.