Harley-Davidson is a motorcycle company.
Homer and Marge won a vintage 1955 Harley-Davidson at a dance competition in Greaser's Cafe. After Bart taught Homer to ride it, he formed a motorcycle gang called the Hell's Satans. Homer fought Meathook with it to win Marge back after Meathook kidnapped her.
Homer later rode the bike down the stairway of his house in Midnight Towboy. Homer also made preparations in You Kent Always Say What You Want to ride his motorcycle through the cemetary after Marge claimed that the family was to do so in an attempt to lure them to the dentist, although Lisa and Bart, who learned the truth minutes earlier, informed him of what was really going on, causing him to admit he thought it was too good to be true.