In models of large extra dimensions, the string and Planck scales become accessible at future colliders. When the energy scale is above the string scale or Planck scale a number of interesting phenomena occur, namely, production of stringy states, p-branes, string balls, black hole, etc. In this work, we systematically study the production cross sections of black holes, string balls, and p-branes at hadronic supercolliders. We also discuss their signatures. At the energy scale between the string scale M-s and M-s/g(s)(2), where g(s) is the string coupling, the production is dominated by string balls, while beyond M-s/g(s)(2) it is dominated by black holes. The production of a p-brane is only comparable to black holes when the p-brane wraps entirely on small extra dimensions. Rough estimates on the sensitivity reaches on the fundamental Planck scale M-D are also obtained, based on the number of raw events.