The following are wrestlers for whom I have been unable to find any solid biographical details. Research is on-going. Match references are mostly from WrestlingData.com, confirmed by newspaper research.
Joe Dillman
aliases: Joe Dalman, Joe Delmas, Joe Hassen, Serge Kotsonaros, Yousseff Hassan, Ali Pasha
Current earlist match: 1 September 1930, Indianapolis, Indiana
Latest reference:
Known career: 1930-1948 (wrestler), -1966 (as promoter, referee)
Selim Omar Hakim
Current earlist match: 21 January 1935, Clarksville, Tennessee
Known career: Jan 1935 - March 1935, all in Meroney/Welch territory
Bulldog Mallory
aliases: Irish Mallory, Clarence Mallory
Current earlist match: 28 January 1931, Waterbury, Connecticut
Known career: 1931-1939
Walter Miller
Current earliest match: 26 January 1933, Sheffield, Alabama
Known career: 1933-1941
Tommy O'Toole
aliases: Dr. X, Red Devil, Red Mask, Yellow Scorpion
Born: 26 April 1913, Phoenix, Arizona (unconfirmed)
Current earlist match: 2 July 1935, Decatur, Alabama
Known career: 1935-1965