The creator of the theory of relativity was created by Albert Einstein. Einstein is a very household name because of the genius of his work.
Einstein's theory included the three dimensions of space and the one dimension of time. these come together to form the four dimensional fabric of space time. Gravity is the warping of space time. This is something Isaac Newton couldn't figure out. the warping can also make time behave unusually. There are objects in the universe called black holes, infinitely dense collapsed stars, they are so heavy, not even ligmt can escape the event horison.