Though no new Clifford episodes have been released since 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 serves as the series finale due to Ritter's death, as no new episodes were made to continue from where it left off (until the reboot in 2019). However, Clifford's Puppy Days still continued to air until its cancellation in 2006.
Two stories made up each half-hour episode. Usually one story featured Clifford and his canine friends, Cleo, T-Bone and Mac among them; the other story would focus on Clifford's owner, Emily Elizabeth and her friends, Jetta, Vaz and Charley. During scenes focusing on the dogs' perspective, human speech would replace barking to show the storyline from the dogs' point of view.
Emily Elizabeth Howard (voiced by Grey DeLisle Griffin; Joanna Ruiz in the British version) is Clifford's 8-year-old owner. Emily Elizabeth adopted Clifford when he was a very small puppy, when her parents gave him to her on her 6th birthday. Emily's love apparently caused Clifford to grow enormous, thus starting their new lives on Birdwell Island. Emily was named for creator Norman Bridwell's daughter and based on the imaginary adventures of Bridwell's wife.
Caroline Howard (also voiced by Grey DeLisle Griffin) is Emily Elizabeth's mom. She owns and works at The Sea Shell, which is a small store on Birdwell Island.
Mark Howard (voiced by Cam Clarke) is Emily Elizabeth's dad and the husband of Caroline Howard.
Samuel (voiced by Terrence C. Carson) is Charley's father and the Jamaican owner of Samuel's Fish and Chips. He runs most of the pier.
Jetta Handover (voiced by Kath Soucie) is Mac's owner. She is a friend of Emily Elizabeth and tends to be snobby towards her. Soucie also voiced Jetta's mother who owns one of the island stores. She often wears her sweater as a poncho.
Cosmo Handover (voiced by Debi Derryberry) is the infant brother of Jetta. He is first seen in the episode "Baby Makes 4".
Welker had also voiced Boomer, a brown capuchin monkey who performs in the circus with Gordo.
Clifford (voiced by John Ritter; Tom Eastwood in the British version) is a big red Labrador Retriever. The depiction of Clifford's size is inconsistent; he is often shown as being about 25 feet (7.6 m) tall from paws to head, but can appear far larger. The character is based on the imaginary friend of creator Norman Bridwell's wife. His owner is Emily Elizabeth Howard.
Cleo (also voiced by Cree Summer; Regine Candler in the British version) is a purple female poodle. Her owner is Mrs. Diller, but she mainly spends the day with her friends Clifford and T-Bone. Her catchphrase is "Have I ever steered you wrong?", and when the dogs would reminisce on a time that happened, she would interrupt them in mid-sentence.
T-Bone (voiced by Kel Mitchell; Benjamin Small in the British version) is a yellow male bulldog. His owner is Sheriff Lewis, but he mainly spends the day with his friends Clifford and Cleo.
T-Bone once had a friend named Hamburger (voiced by Kel Mitchell's longtime comedy partner Kenan Thompson) who moved away before Clifford arrived.
Mac (also voiced by Cam Clarke) is a blue male greyhound. It is revealed in a few episodes that his name is short for Machiavelli. His owner is Jetta Handover.
K.C. (also voiced by Cam Clarke) is a male dog who only walks on three legs. He is one of Clifford's, Cleo's and T-Bone's best friends.
Mimi (voiced by Tyisha Hampton) is a female poodle and T-Bone's love interest who occasionally visits Birdwell Island.
Rex (voiced by Frank Welker) is Clifford's friend from the time when he was still a puppy.
Emily Elizabeth used to live in an apartment in New York City, but she moved away with her parents and Clifford to Birdwell Island because Caroline told her that a small apartment is no place for a big dog like Clifford.
The series has at least 4 segments in the show.
First story: The opening theme is followed by the first central story, which is usually about the dogs, and a problem they face.
Storytime with Speckle: Between the first and second story, Emily Elizabeth reads Clifford a short story about a dog named Speckle, and his animal friends.
Second story: Another central story, usually about Emily Elizabeth and her friends.
Clifford's Big Ideas: Another 30-second short, which demonstrates a moral lesson such as "Play Fair" or "Help Others", with narration by Emily Elizabeth. This segment is sometimes cut-out on PBS Kids Channel airings.
Live action segments starring real kids and their dogs.
In the UK version, only one story is shown, with either the Storytime with Speckle or the Clifford's Big Ideas segments at the end, shortening the show to about 15 minutes.
Clifford the Big Red Dog has received generally positive reviews from television critics and parents of young children. Lynne Heffley of Los Angeles Times wrote," Clifford: The Big Red Dog focuses on positive messages with a fantasy approach. Based on the classic children's books by Norman Bridwell, this animated series is about a red dog who is the size of a jumbo jet to match the outsized love that his owner, a little girl named Emily, has for him."
On May 16, 2018, Scholastic announced a reboot of the series, which premiered on December 6, 2019, for both Amazon Prime Video and PBS Kids.Scholastic, 100 Chickens, 9 Story Media Group and Brown Bag Films produce the series. Excepting Clifford, Emily Elizabeth and Birdwell Island, the new series is a complete departure from the predecessor show's character base.
In other media
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In 2004, Warner Bros. Pictures distributed a feature-length animated film based on the show, Clifford's Really Big Movie. In the film, Clifford, Cleo and T-Bone join an animal show to win a lifetime supply of dog food to provide for Clifford. This was one of John Ritter's last films as he died on September 11, 2003, after completing voice work for the film. Clifford's Really Big Movie was dedicated to his memory. The movie also stars Wayne Brady as Shackleford the Ferret, Judge Reinhold as Amazing Larry, John Goodman as George Wolfsbottom, and Jenna Elfman as Dorothy the Cow. The film also serves as the series finale, as no new episodes were produced after the film was released, until the reboot premiered on PBS Kids in 2019.
Clifford's Thinking Adventures
Clifford's Learning Activities
Clifford's Musical Memory Games
Clifford's Big Puzzle Game (A Wendy's Kids' Meal DVD game, available for a limited time only)