George Hubbard Clapp (December 14, 1858 – March 31, 1949) was an American pioneer in the aluminum industry and also a numismatist.

He was born on December 14 in Allegheny City, Pennsylvania, now a part of Pittsburgh, the son of Delia Dennig Hubbard and DeWitt Clinton Clapp, an iron company executive.

Clapp took an engineering position at Park Brothers' Black Diamond Steel Works.

There, along with Captain Alfred E. Hunt, he established the Pittsburgh Testing Laboratory's chemistry department.

Hunt formed a company in 1888 to exploit the Charles Martin Hall patents for making aluminum by electrolysis.