Robert P. Alexander (November 26, 1904 – August 24, 1985) of Washington, D.C., was a collector and expert on Japanese classic postage stamps.

Although his collecting interests covered the entire scope of stamps and postal history of Japan, he studied and became expert in certain issues, such as the Dragon issues.

Alexander wrote articles on specific aspects and postal issues of Japanese philately.

He was a founder of the International Society for Japanese Philately in 1946 and once served as its president during his forty years with the society.

Robert Alexander was inducted into the American Philatelic Society Hall of Fame in 1986.