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.
1968
2024
2019
1916
1928
1924
1926
2011
2016
1925
1915
1921
2017
2015
1994
1991
1939
2008