Not sure how well known it is... but the example that has always stuck out in my mind is the niche Xbox360/PS3 JRPG "Eternal Sonata"
According to the game: On the night of his death, legendary Polish composer and piano player Frederic Chopin had a dying fever dream that saw him transported to an anime fantasy world that may or may not be of his own mental creation. Now, as the hours tick away on his final night on earth, he has to come to terms with the dubious reality of his situation, the problems of the cast that has surrounded him, and his own mortality and legacy.
Now, that's a little bit morbid, and I can't speak to the tastefulness of using a real person for it... but it's such a zany amalagam of concepts that I can't deny I was interested. I wanted to see where they were going with it, and what sorts of answers Chopin would find on his bizarre little journey.
... Unfortunately, about an hour after he's first introduced in the fantasy world, Chopin quickly becomes a secondary support character in his own dying dream. The plot completely forgets about him for 40-50 hours, and decides we'd be much more interested in a cliche "evil lord oppressing the populace of an anime fantasy land" story mixed with the JRPG standard, chemistry-devoid, romance between teenagers. The game doesn't remember him again until after you've beaten the penultimate boss... at which point he basically goes "Oh yeah! This was supposed to be my story!" and suddenly becomes the final boss fight. If he beats the party, he wakes up in the real world; if he loses to the party, he implicitly accepts his death and moves on.
I mean, there are some interesting implications there... would have been nice to have them explored by the game, instead of it just being a thing that got tacked onto the end of an otherwise unrelated anime adventure. It was one of the first times I felt like a game had completely sold me a lie. At least the soundtrack was nice.