Grim Grinning Ghosts was written for the Disney attraction in the late 1960s. It was composed by Buddy Baker, with lyrics by X. Atencio. Taking its name from a line in the Shakespearean poem, Venus and Adonis, variants of the song are played throughout different areas of the Haunted Mansion ride, with the lyrics first being heard in the graveyard scene. Thurl Ravenscroft (how Halloween-y does THAT name sound?) is one of the voice talents in Grim Grinning Ghosts---you might recognize him from other projects, including the voice of Tony the Tiger! His face can also be seen superimposed on one of the busts in the graveyard scene. Give it a listen below, and then check out the links provided for more information.
10 Things to Know About the Haunted Mansion Theme 'Grim Grinning Ghosts'