What was the famous cliffhanger question from 'Dallas' in 1980?

In 'Yellowstone', what is the name of the family that owns the ranch? Who plays John Dutton in 'Yellowstone'? In 'Downton Abbey', what is the family's surname? In 'Dallas', what is the name of the scheming oil baron? In 'Happy Days', what is Fonzie's full name? Which phrase comes from 'Happy Days' and means a show has passed its peak? In 'I Love Lucy', who played Lucy Ricardo? In 'I Love Lucy', what is the name of Lucy's husband?