*The Titanic never sank
Hollywood would have capitalized off of a different tragic accident.

*JFK or Martin Luther King were never assassinated
nothing

*The Stock Market Crash of 1929 never occurred
i agree with ars, something terrible would have happened anyway at a later date. probably in 1930

*The Black Death didn't sweep Europe at all.....just a few cases here and there.
super AIDS would sweep.