Ritter was also nominated posthumously in 2004, losing to Kelsey Grammar for Frasier.
Sagal portrayed his wife, the family's voice of reason, Cuoco his eldest daughter, the stock ditzy blonde.
Ritter, an icon in the world of American television for his star turn on Three's Company, died in 2003 from a misdiagnosed thoracic aortic aneurysm.
The 54-year-old had been rushed to hospital straight from a rehearsal for 8 Simple Rules For Dating My Teenage Daughter.
The final series, its title trimmed down to 8 Simple Rules, ended in 2005, having won a cinematography Emmy in 2004.
It goes without saying that we were all fortunate to have a few final moments of John doing what John did best, and that's just one of the things that made 8 Simple Rules a standout.