|Friends||T-Bone, Cleo, Mac|
|Families||Emily Elizabeth Howard (owner)|
|First appearance||My Best Friend|
|Voiced by|| John Ritter (original series, "Clifford's Really Big Movie")|
Lara Jill Miller ("Clifford's Puppy Days"<be>Frank Welker (PBS Kids "Ready to Learn" bumpers)
Clifford, also known as Clifford the Big Red Dog is the big red dog of Emily Elizabeth's and is also the main protagonist of the show. He was voiced by the late John Ritter. Clifford is the main character. Clifford's size is caused by the amount of love Emily Elizabeth gave him.
Clifford is a helpful, outgoing and a friendly dog and clumsy. He will always help his buddies in their times of need and give them amazing advice. However, being kind and understanding doesn't prevent him from having standards. He also can be gullible and naive and sometimes believes everything he is told. In one episode, a dog tricked him into digging someone's hole and got Clifford blamed for it. Clifford has a tag in Clifford's Really Big Movie.
Clifford is a very big red dog, which sometimes he gets into trouble because of his size or is tempted into trouble by his friends and those he meets. His size, like giants in medieval legends, is inconsistent—he is often shown as being about 25' tall from paws to head, but can appear far larger. Emily Elizabeth gave him a huge amount of love, this caused his big size.
- Clifford is John Ritter's only voice over. After Ritter's untimely death from aortic dissection PBS announced they would end the series.
- Although Ritter passed in 2003, his voice can be heard as Clifford as late as 2004 because "Clifford's Really Big Movie" was released posthumously.
- If Ritter didn't pass away, the series would've ended with Clifford getting married and having big red puppies.
- Clifford was given a prequel series "Clifford's Puppy Days" and it takes place before the Howard's move to Birdwell Island. In this series Clifford is played by Lara Jill Miller.