This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”
http://www-history.mcs.st-and.ac.uk/~history
This is an award-winning site that links to all sorts of mathematics information.
https://mathshistory.st-andrews.ac.uk/HistTopics/History_overview
Here are the biographical sites related to this section:
Euclid: https://mathshistory.st-andrews.ac.uk/Biographies/Euclid.html
Proclus: https://mathshistory.st-andrews.ac.uk/Biographies/Proclus.html
Legendre:
https://mathshistory.st-andrews.ac.uk/Biographies/Legendre.html
Bolyai:
https://mathshistory.st-andrews.ac.uk/Biographies/Bolyai.html
Playfair:
https://mathshistory.st-andrews.ac.uk/Biographies/Playfair.html
Lambert:https://mathshistory.st-andrews.ac.uk/Biographies/Lambert.html
Gauss:
https://mathshistory.st-andrews.ac.uk/Biographies/Gauss.html
Lobachevski:
https://mathshistory.st-andrews.ac.uk/Biographies/Lobachevsky.html
Riemann:
https://mathshistory.st-andrews.ac.uk/Biographies/Riemann.html