One overlooked gem from the late 60's was "Do Not Adjust Your Set". Stellar cast: Eric Idle, Michael Palin, Terry Jones, who a year later would form Python (in its second season, Terry Gilliam had a few cartoons shown), David Jason (the future voice of Danger Mouse) and the Bonzo Dog Doo Dah Band, who performed brilliant song parodies, and whose Neil Innes joined Python as well.
Used to air in England at 5:30 pm. Even though it was geared for kids, adults would rush home from work to catch it. Kinda like an ultra-hip Sesame Street.