William Carpenter (February 25, 1830 – September 1, 1896) was an English printer and author, and a proponent of the flat Earth theory, active in England and the United States in the nineteenth century. Carpenter immigrated to the United States and continued his advocacy of the Flat Earth movement.

Carpenter was born on February 25, 1830 in Greenwich, Kent, England and he was baptized on April 30, 1830 at Maize Hill, formerly known as Bethel - Independent in Greenwich. He was the eldest son of Samuel Carpenter and Lucy Moss. He married Annie Gillett January/March 1853 and they eventually had six children.

In Greenwich, Carpenter became a printer and stenographer by profession. In 1879, he moved from England to Baltimore, Maryland, where he continued his work as a printer. The 1880 U.S. federal census shows him and his wife Annie with six children aged 11–25 years whose occupations included milliner, architect, professor of music, and florist.

After arriving in Baltimore, Carpenter taught classes in shorthand. He published two books on the subject and became known as "Professor Carpenter." Carpenter had other eclectic beliefs per his Baltimore Sun obituary. "For many years Mr. Carpenter had also been a vegetarian, a believer in the power of mesmerism and a spiritualist. Upon each of these questions he wrote pamphlets. He thought that the eating of meat was responsible for many of the ills that humanity is heir to."

Carpenter died on Tuesday September 1, 1896 at 1316 North Central Avenue, his home, in Baltimore. Per his obit in the Baltimore Sun, his death was the result "... to a stroke of apoplexy on Sunday." In the year before his death he had "... a number of slighter strokes ..."