Photo manipulation is as old as photographs themselves!
The Victorians came up with several clever tricks to make photographs more entertaining, e.g., they used photomontage and combination printing to produce headless portraits, inspired by popular stage magicians. Double exposure was also used to add objects not present in the original exposure, such as ghostly figures or floating items. Unfortunately, some people used these techniques in a more questionable way.
A few photographers started working as mediums and marketed their spirit photographs as evidence of the afterlife. The spiritualist movement quickly adopted the use of spirit photography and published numerous books on the subject.
Check out some quirky headless photos here.