The first person to earn a PhD in Computer Science is not whom you'd expect.

https://en.m.wikipedia.org/wiki/Mary_Kenneth_Keller

A Roman Catholic nun was the first person (not woman) in the U.S. to earn a PhD in computer science, and tied for first if we mean “doctorate”.

This was in her 50s, after having previously earned an undergraduate degree in mathematics and a master’s degree in math and physics, around ages 30 and 40.

Then, with a PhD earned that late in life, she founded what was among the first computer science academic departments at a small college, and ran it for two decades, and published in the field.