There are two distinct Gleason families, the English and the Irish. The English family was originally Leeson, Leson, Leason, etc. The Irish is believed to have been originally Gleeson. Obviously any name with son at the end refers to the "son of" therefore take your choice, Gleason is the son of Lee, Le, Lea, Gle, Glea, etc. In either case the name is old ... before the 1500's when most were illiterate and spellings were generally phonetic. I read once in the newspaper in a superficial and rather stupid piece that "Gleason" meant "Little Green Man."