Question

Is there somebody in your community who has made a significant contribution in their field of Mathematics but is yet unknown?

Answer 1

How "significant" of a contribution?

Look at every phd thesis in mathematics. Every year produces more. These typically need to contain some original contribution to human knowledge (at least traditionally, they did...) and most phd graduates are fairly unknown. So you could find them everywhere, every year.

Answer 2

It depends on how you measure whether a contribution is significant or not. Normally, I would call a contribution significant if the experts in the area indicate this by either accepting the article on it in a top ranked journal or inviting the contributors to give talks. At that point, you can't call the person unknown. But sometimes they were relatively unknown before they did the significant work.