The A. C. Gilbert Company was an American toy company, once one of the largest in the world. Gilbert originated the Erector Set, which is a construction toy similar to Meccano in the rest of the world, and made chemistry sets, microscope kits, and a line of inexpensive reflector telescopes. In 1938, Gilbert purchased the American Flyer, a manufacturer of toy trains. The Gilbert Company struggled after the death of its founder in 1961 and went out of business in 1967. Its trademarks and toy lines were sold to other companies.

Erector Set was a brand of metal toy construction sets which were originally patented by Alfred Carlton Gilbert and first sold by his company, the Mysto Manufacturing Company of New Haven, Connecticut, in 1913. In 1916, the company was reorganized as the A. C. Gilbert Company. The brand continued its independent existence under various corporate ownerships until 2000, when Meccano bought the Erector brand and consolidated its worldwide marketing with its own brand. The coverage here focuses on the historical legacy of the classic Erector Set; for current developments under the "Erector by Meccano" brand name, see the Meccano article.