|~ Happy Chapmen's catchphrase.|
|“||Oh, please, what a know-it-all! And everybody always said I was the handsome one, I was the smart one, and I was born first. But there you are, "live from the Hague". And here I am working with this sack of dander on a dead-end regional morning show.||„|
|~ Chapman's jealousy towards his anchor brother Walter, also revealing his true colors.|
While he may look like he lives up to his name with friendly and polite, Chapman is actually a very arrogant, pompous, greedy, deceiving, and manipulative person. He is allergic to cats, and wants a dog to star in his show to overshadow his more successful twin brother, Walter in jealously. Chapman believes that he has found his perfect star when he discovers Odie and later steals the dog for his own gain like Odie. He is extremely cunning, deceitful, and treacherous when he outwits Walter in success. He is also shown to be severely argumentative, unpleasant, and abusive towards his assistant, Wendell. He is also sadistic and ruthless. His brother Walter referred to him as his idiot brother at the end.
Happy Chapman is a TV host who expresses true happiness on his show using his cat Persnikitty as an example, but later reveals that he is actually an arrogant, greedy, selfish man who is severely allergic to cats, abuses his butler Wendell and is dissatisfied with his job as TV pet show host. Chapman wishes for a dog to star in his show so he can overshadow his more successful twin brother, Walter the news anchor in fame and expresses his jealousy towards him as well.
Later on, Jon and Odie go on a date with Liz (with Garfield towing along) where she is judging a dog show, where Chapman also happens to be one of the judges. Garfield accidentally enters through the curtain that leads to the stage, and all the dogs chase after him. To stop the chaos, the dog show host orders the DJ to start the music. The DJ turns on the radio and Black Eyed Peas' "Hey Mama" (the same song Garfield and Odie danced to earlier) starts playing, and Odie runs out of Jon's lap and does his little hind dance, and steals the show, becoming the unexpected winner. Chapman, amazed by Odie's extreme talent, tries offers Jon to make him his new star pupil, but Jon respectfully declines as he wishes to have a normal pet. Chapman, hiding his anger, still gives Jon his business card in case he changes his mind before looking at Odie with his greedy eyes.
When Odie ran away from home due to Garfield locking him out, Chapman, taking advantage, lied to Mrs. Baker, the elderly woman who put up the poster, that Odie was his dog and put him in his show before he (presumably) placing Persnikitty in the pound. He then took out a dreaded shock collar, despite Wendell reminding him that he promised he'd never use the collar, claiming it to be cruel and inhumane. Chapman dismisses Wendell's concern, claiming the collar to be Odie's "future" and threateningly asks Wendell if he has a problem with that, to which Wendell timidly responds "no."
Meanwhile, Garfield notices Odie on The Happy Chapman Show when he surfs through the channels on the TV. Upon learning that Chapman plans to move the set to New York City, Garfield, in his nobelist decision yet, leaves the house to go to the Telegraph Tower (the tall building where they film Chapman's show) to find Odie.
After a series of mishaps, Garfield finally manages to make it to the Telegraph Tower, and eventually finds Odie in Chapman's office. Garfield apologizes to the dog for how much of a jerk he's been to him. Before Garfield can free Odie, however, Chapman and Wendell enter the room, forcing Garfield to hide. Chapman places the shock collar on the dog's neck, then activates it, creating a powerful and painful electric jolt that forces Odie to do back-flips. Chapman even sadistically laughs at the dog's pain from the powerful jolts, before he and Wendell leave the building to catch their train. Disgusted at Chapman's actions, Garfield tries to follow him, but gets captured by Animal Control and is locked up in the pound.
Meanwhile, Jon and Liz arrive at Mrs. Baker's house after seeing Odie's poster, only for her to tell them that Chapman had already taken him. Realizing Chapman tricked her into believing Odie was his dog, Jon and Liz rush off to find Chapman and rescue Odie and Garfield.
At the pound, Garfield is surprised to see Persnikitty in another cage. Persnikitty explains that he is furious at Chapman's betrayal towards him by replacing him with Odie before coldly throwing him in the pound and his real name is really Sir Roland. To get back at his former owner, Sir Roland collaborates with Garfield on an escape. When a family arrives at the pound to adopt a cat, Sir Roland takes advantage, realizing that it is the perfect opportunity for escaping the pound. Just as he is about to be given to the couple's daughter, Sir Roland runs out of the pound officer's arms and presses the red emergency button, which opens all the cages and all the dogs and cats flee out the door. Garfield resumes his search and heads for the train station.
Back at the Telegraph Tower, Jon and Liz arrive at Chapman's office and Jon sees cat pawprints on the floor and realizes Garfield had been there. A security guard suddenly comes up from behind Jon and Liz and asks them if they need help from him. Jon tells the security guard that they're looking for Happy Chapman, and the guard tells them that Chapman is on his way to the train station and taking a train to New York City, and Jon and Liz rush out and head for the train station as well.
At the train station, Garfield is too late to stop Chapman's train from departing. Jon and Liz also see the train depart and rush to the reception desk and beg the receptionist to stop the train, but she tells them there is nothing she can do about it. However, Garfield sneaks into the control room, sabotages Chapman's train route by frantically switches the tracks, that leads to an impending train wreck and manages hits an emergency control to make the train return to the station. Garfield reunites with Odie, and the two escape. However, Chapman sees them escaping through the train's window while getting in a fight with some waiter and conductor, and he rushes out of the train and gives chase at them.
Chapman eventually corners Garfield and Odie in the luggage area and threatens Odie with the shock collar before he grabbing the latter to put the shock collar on him again. Angry that Happy will abuse Odie and make him perform against his will, Garfield lunges at Chapman, but an evil Chapman tosses him aside. However, the pound animals that Garfield helped free (led by Sir Roland) arrive to the rescue Odie from Chapman, who cowardly tries to escape, and as they corner Chapman. Chapman gets scratched and bitten by numerous cats and dogs, while the rats place the collar on his own neck. Garfield and Odie give Chapman two electric jolts as a satisfying payback. Jon and Liz then arrive and come face to face with the dazed Chapman. Jon furiously punches Chapman in the face for stealing his pets and then is reunited with Garfield and Odie. Happy Chapman is then arrested by the police and sent to jail for his crimes during on the news coverage by a reporter, Abby Shields making her report about Happy (referred as "deranged man") with his shock collar and complaining crazily. As Happy is arrested, Walter while on the air takes another jab at his humiliated brother before signing off.
After Chapman's arrest, it is presumed that his show is now officially canceled and suffers his losses of his fortune as he remains in prison.
- Booger, a minor hero from the 2002 Rob Schneider comedy film The Hot Chick, may bare a slight resemblance to a younger version of Chapman.
- Happy has a strong dislike for lasagna, which ironically is Garfield's favorite food.
- Thomas Lennon, Michael Ironside, Brad Dourif, Steve Zahn, Christopher Walken, Joseph D. Reitman, John Lithgow, and Wilmer Valderrama were all considered for the role of Chapman before Stephen Tobolowsky was cast.