Dr. Sigmundheimer F. "Siggy" Rhoid, M.D., Ph.D., B.S. (b. May 6, 1961) is an Austrian-American psychiatrist and Yu-Gi-Oh! player who is perhaps the world's foremost authority on internet-related mental illness, particularly those relating to the use of anonymous web-based communities, such as MUDs, MMORPGs, and wikis. Known primarily for his work with wiki users, Rhoid's theories regarding the interpersonal abuse of multi-user anonymous websites of all varieties generally include the following hypotheses: