Due to his research into hormone-based contraceptive methods, which also involved brutal human experiments in the Auschwitz extermination camp, which Nazi war criminal is considered one of the fathers of the contraceptive pill?

The Nazi most directly associated with early research into hormonal contraception is Carl Clauberg.

Carl Clauberg was a Nazi doctor who conducted horrific sterilisation experiments on prisoners at Auschwitz, particularly Jewish and Roma women. His research focused on the use of hormonal treatments and injections to induce infertility, an approach that indirectly contributed to later developments in reproductive medicine, including hormonal contraception.

Although Clauberg's work was carried out for the purpose of coercive sterilisation, some of his research on hormones later influenced medical studies on fertility regulation. However, his name is not celebrated in scientific circles because of the inhumane nature of his experiments.

https://en.wikipedia.org/wiki/Carl_Clauberg