Saturday Night Live (SNL) is the longest-running sketch-comedy program of all time. It started on NBC in 1975 under the watchful eye of Lorne Michaels, and its cast was dubbed the "Not-Ready-For-Primetime Players" in the media. Most of the early cast went on to great success in primetime as well as the silver screen, and that tradition continues today (or, at least, within the five few years). Lorne Michaels has remained the producer throughout its 35 year lifespan.
Each SNL broadcast has a famous guest host (who is ready for primetime) and musical guests of varying fame. It is not uncommon for the musical guests to be considerably more famous than the host, such as when John Turturro hosted with Tom Petty & The Heartbreakers as the musical guests.
In addition to the cast venturing onward to the silver screen, some SNL characters have had full-length motion pictures (albeit, rarely to any tremendous success).