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.
1976
2014
1914
2017
2016
1933
1937
2011
2018
2020
2015
2021
2010
2024
1983
2006
2023
2022
1922
1990