The Horror of It All (1964)

In this dark comedy, a Yankee goes to visit a family of British eccentrics to ask for the hand of one of their daughters in marriage. He soon finds himself in the midst of a really odd family. One of them talks like Bela Lugosi, another believes herself to be a vampire, while a third is locked away in a padded cell. Another family member is thrilled when he finally invents a horseless carriage (50 years after Ford), and the family grandfather is found reading Playboy just before he dies. Trouble begins when members of the family begin to be mysteriously murdered. The American suitor must then discover which member of the strange family is in line to inherit the family fortune.