Clifford the Big Red Dog is an animated educational children's television series, based upon Norman Bridwell's children's book series of the same name. Produced by Scholastic Productions, it was originally aired on PBS Kids from September 4, 2000, to February 25, 2003. A UK version (dubbed with British voice actors replacing the original American soundtrack) originally aired on BBC Two in April 2002.

Internationally, German-based TV-Loonland AG handled broadcast rights to the series, while Entertainment Rights held merchandising and home media rights.

John Ritter voices Clifford in every episode. By the time the series ended production and the subsequent film Clifford's Really Big Movie were completed, Ritter was back on ABC's prime time schedule, starring in 8 Simple Rules. Ritter's death on September 11, 2003, came ten days after the debut of Clifford's Puppy Days (it is often mistakenly cited as the reason the spin-off was created in lieu of a third season).

Though production of Clifford ended before Ritter's death, voice actors for the main characters have reprised some of their roles for the Ready to Learn PBS Kids PSAs. Clifford's Really Big Movie served as the series finale, Clifford's Puppy Days still continued to air until its cancellation in 2006.

On May 16, 2018, Scholastic announced a reboot of the series, which was released on December 6, 2019, on Amazon Prime Video and December 7, 2019, on PBS Kids, starring Adam Sanders as the new voice of Clifford. PBS Kids continued to air reruns of the 2000 series on some PBS stations until 2022. Select PBS member stations still continue to carry the show.

As of 2021, the show is currently distributed worldwide by 9 Story Media Group.