Turtledove effect
n. In a work of alternate history, the implausible insertion of characters or events from the original timeline.
Also Seen As
neologism:Turtledove Effect: Inserting historical characters into an alt. history long after the Point of Divergence makes them unlikely.
—Paul Weimer, “neologism…,” Twitter, March 05, 2015
It's what I call the Turtledove effect: take a good premise but then add massive amounts of OTL people with widely different careers and over-analogise conflicts in terms of Nazis and Soviet Regimes.
—The Professor, “AH fiction that deserves a film/tv adaption” (reply), Alternate History, May 18, 2011
2003 (earliest)
"Mike Schilling" <mscotts…@hotmail.com> wrote in message
news:[email protected]

> Similar effect: AHs where the characters discuss one and only one AH: our
> timeline:
> "Imagine, for instance, what the world be like if George Washington hadn't
> died of plague in the 1779 epidemic. He might have rallied the rebels to a
> victory, leading to independence for the colonies and revolution on the
> continent of Europe."

Isn't that the "Herry Turtledove" effect [sic]?

—Mark Hanson, “Is there a formal term for this?” (reply), rec.arts.sf.written, June 05, 2003
In online discussions of alternate history, the abbreviation OTL stands for either original timeline or our timeline.