Turner Broadcasting System
This Atlanta-based cable channel began as WTCG, then changed its call sign to WTBS as its U.S. cable coverage increased. Now known as TBS, and separate from the Atlanta station (now known as WPCH, "Peachtree TV", which split in 2007 to allow TBS to carry Major League Baseball games involving teams other than the Braves) it and the other Turner properties currently belong to Time Warner.
Its secret weapon was "Turner Time", scheduling programs 5 minutes after the top of the half/hour in order to make sure viewers would miss the beginnings of other channels' fare and thus be resigned to stay with TBS for another show.
Back in the 1990s, most TV watchers referred to TBS as "The Beastmaster Station" because of its frequent showing of the film "The Beastmaster".
In June 2004, in response to sibling TNT's post-2001 focus on dramatic programming (and possibly Time Warner's divestiture of its stake in Comedy Central to Viacom the previous year), it decided to situate itself into the genre of comedy, after years of not having a genre (the comedy focus is a little looser than TNT's on drama, though, as evidenced by the movies it tends to run). To that end, on April 12, 2010, Conan O'Brien announced a five-year deal with TBS to do an 11 PM talk show.
Not to be confused with Tokyo Broadcasting System (original broadcaster of a significant amount of significant anime) or any other broadcaster called "TBS".