It is called the Time Traveler's Paradox. In which a scientist creates a Time Machine and kills their younger self. So now a man who should not- can not- exist, somehow does. That is the Paradox, and Paradoxes are impossible.
2005
1915
2010
2017
2000
2016
2006
2024
2018
1926
2023
1952
1951
2011
2004