Thriller is a British television series, originally broadcast in the UK from 1973 to 1976. It is an anthology series: each episode has a self-contained story and its own cast. As the title suggests, each story is a thriller of some variety, from tales of the supernatural to down-to-earth whodunits.

This programme is the original version of the popular Channel 4 words and numbers show, Countdown Countdown.Yorkshire Television purchased the format and commissioned a series of eight shows under the title Calendar Countdown, which were to be a spin-off of the regional news programme Calendar. As the presenter of Calendar, Richard Whiteley was the natural choice to present Calendar Countdown his daily appearances on both shows earned him the nickname "Twice Nightly."