Jody Enders wrote in 1998 about a 1878 French account of a play performed in 1549, in which the dramatic onstage execution was no special effect, but used a condemned prisoner whose head was cut off onstage. Considering how many times the story must have been told between those written accounts, it is probably an urban legend. Probably. Read Enders' full account or the short version at TYWKIWDBI. Link