Happy Chapman (portrayed by Stephen Tobolowsky) is a television host and the main antagonist of the film, who features house pets on his show. He kidnaps Odie, thinking that he will make him a star. Happy's catch phrase is "Be Happy!".
Likes: Fame, money, getting what he wants, outwitting his brother Walter in success, pets, dogs.
Dislikes: Not getting his way, Walter being more famous, cats, poverty, not having dogs.
Goal: To outwit his brother Walter J. Chapman in regards to success, keep Odie as his own dog, perform on Good Day New York.
Friends: Wendell his butler, Mrs. Baker (formerly)
Enemies: Walter J. Chapman, Odie, Persnikitty, Garfield, Jon Arbuckle, Liz Wilson, police, train conductors.
Fate: Is arrested for his crimes.
Happy Chapman is a TV host who expresses true happiness on his show using an example of his cat Persnikitty as an example but later reveals that he is an unhappy selfish man. His goal in life is to outwit his TV anchorman brother Walter J. Chapman who apparently took over the anchorman position of the channel that Happy's show is on. Happy Chapman reveals to be severely allergic to cats and wants to get a dog act in order to perform on the better TV show than he and Walter's channel; Good Day New York and not to have to work under Walter as the channel anchorman. Chapman is invited to judge a local judge show and there he and his butler Wendell see a dog named Odie perform well and end up winning the first place prize. Chapman links Odie to his owner Jon Arbuckle where he offers Jon a TV show offer but when Jon refuses Chapman pretends to accept the refusal and walks off.
However when Chapman and Wendell realize that Odie has run away from Jon because of Odie's roommate pet Garfield the cat, they decide to use this as an advantage to steal Odie from Jon by tracking the woman that found him; Mrs. Baker and look as if they are Odie's owners. Happy Chapman then sells his cat Persnikitty to the local dog pound. However Garfield has regretted his actions to let Odie run away; and pursues Chapman when he learns that Chapman, using Odie's talents, will perform on Good Day New York. Garfield manages to reach telegraph tower where Chapman's headquarters are, and catches Happy Chapman using a shock collar to control Odie into performing nice clever tricks to practice for his new show job at Good Day New York. A furious Garfield decides to follow Chapman to his transporation but is briefly captured by dog pound agents until he with help from other animals escapes. Chapman, and Wendell flee on a train to New York with Odie but Garfield manages to manipulate the switches of the tracks to put Chapman's train where it started. As the train station staff and customers becomes confused by this unintended occurance Garfield uses the distraction and frees Odie and they both walk out. However Wendell points out their escape to Chapman who gives chase. Chapman corners Garfield and Odie in the luggage room before putting the shock collar on Odie and throwing Garfield into luggage piles when Garfield pounces at him. However Chapman is shocked when Persnikitty his old cat has not taken his replacement well and to avenge against his former master, Persnikitty leads the pound animals, Garfield and Odie into attacking Chapman. Eventually Chapman's shock collar is put on himself and Garfield shocks him twice. When Chapman wakes up he sees Jon, Liz Wilson (Jon's friend) and a mob of police officers enter.
Happy Chapman realizes that Jon had found the lady he took Odie from Mrs. Baker, had learned of his intentions to steal Odie (Unaware to Baker though) and got the police on his side. Happy Chapman is unable to defend himself from the accusations of both stealing Odie, a mistaken charge of causing the train switching and then a mistaken crime of stealing Garfield; thus he is arrested by an angry mob of police officers, train passengers and security guards as well as Wendell for his part in stealing Odie.
Since he is not mentioned in Garfield 2: A Tale of 2 Kitties a year later nor that Chapman has tried to pursue Odie anymore; it is presumed that Happy Chapman was found guilty of the charged crimes (see above), his show and part in Good Day New York was probably cancelled and he is most likely currently serving a prison sentence with Wendell.
- Happy Chapman may be a parody of comedian Soupy Sales.
- Happy Chapman is the direct opposite of Garfield as he hates lasagna.