The woman with the most, Margaret Court won 24 in the 1960s and early 1970s, dominated when very few women played sports, and dominating then is not even close to dominating now. She was a great player, but in a more competitive age, there is no way Court would have won more grand slam titles with Serena. Steffi Graf is 2nd in grand slam titles with 22. She was an amazing athlete, and a legit argument could be made that she should still be considered a more dominant player (and athlete) than Serena. I don't think Serena is done yet, but I don't see her getting 4+ more GS titles to tie or pass Graf.