Alessandro Trotter (26 July 1874, Udine – 22 July 1967, Vittorio Veneto) was an Italian botanist and entomologist who pioneered in cecidology, the study of plant galls.Alessandro Trotter was the son-in-law of Pier Andrea Saccardo (1845–1920). His first work on cecidology dated back to 1897 (when he was 21 yrs old) and he reported 124 galls of which 21 were caused by eriophyid mites. Trotter travelled around Italy between 1899 and 1909 and described 742 galls in 20 papers.