Once, long ago, a man thought to use 0 as a place holder in out number system, and that one person made modern mathematics possible. Did he just get catalogued under 'great person'? No! We arn't even sure who it was, but he was darn useful!
... Because this falls under the wide umbrella of "things that have been pissing me off recently," I'm going to correct you.
1. There are in fact a good number of female mathematicians. If you want one from the ancient era, go with Hypatia. More recently, and more famously, Amalie Noether and Sonya Kabalevskaya. "Once, long ago,
someone thought to use 0..."
2. It wasn't "one person." A number of ancient civilizations came up with the concept of zero. Plus, as you may or may not know, concepts like that usually take a large number of individuals to come up with, because you don't get mathematicians in vacuums.
3. Zero is nothing (hurr hurr) compared to the discoveries of people like Cauchy, Newton/Leibniz (thrown in because his notation is better) and Godel. In the range of concepts "making modern mathematics possible," zero is about equivalent to Russel's Paradox in terms of significance. The inventor would never be known to the main public, anyway, because if all they did of importance was figure out 0... well, frankly, no one really gives a damn about something like that.
If you meant "modern mathematics" in terms of "what we teach elementary school students," I'll have to say that whoever/whichever group came up with 1 and/or moved us to the decimal system was probably more fundamental.