He appeared in over 100 films and television series combined and performed on Broadway, with roles including adult Ben Hanscom in It (1990), Problem Child (1990), Problem Child 2 (1991), a dramatic turn in Sling Blade (1996), and Bad Santa in 2003 (his final live action film, which was dedicated to his memory).

His final roles include voicing the title character on the PBS children's program Clifford the Big Red Dog (2000–2003), for which he received four Daytime Emmy Award nominations, and as Paul Hennessy on the ABC sitcom 8 Simple Rules (2002–2003).

Johnathan Southworth Ritter was born on September 17, 1948, at Providence Saint Joseph Medical Center in Burbank, California.

[3]His father, Tex Ritter (1905–1974), was a singing cowboy and film star, and his mother, Dorothy Fay (née Southworth; 1915–2003), was an actress.

Ritter became a household name on Three's Company, portraying struggling culinary student Jack Tripper with two female roommates.

Detective Harry Hooperman inherits a run-down apartment building and hires Susan Smith (Debrah Farentino) to run it.

He co-starred with Jim Belushi in 1987's Real Men and played the lead role in Blake Edwards' 1989 film Skin Deep.

Ritter starred in many television films, including Gramps (1995), co-starring with Andy Griffith, Rob Hedden's The Colony (1995) with Hal Linden, Stephen King's It, Danielle Steel's Heartbeat with Polly Draper, and It Came from the Sky in 1999 with Yasmine Bleeth.

Ritter also made guest appearances on television shows, such as Felicity, Ally McBeal, Scrubs, Buffy the Vampire Slayer, and Law & Order: Special Victims Unit.

[9][10] In 2000, Ritter co-starred with Henry Winkler in Neil Simon's The Dinner Party at the Music Box Theatre on Broadway, portraying Claude Pichon.

In 1991, both were guest stars on The Cosby Show, in which Yasbeck played the in-labor wife of Ritter's basketball coach character.

On September 11, 2003, Ritter was rehearsing for 8 Simple Rules... for Dating My Teenage Daughter on the Walt Disney Studios lot in Burbank, California when he suddenly fell ill: sweating profusely, vomiting, and complaining of chest pain.

Ritter was initially treated by emergency room physicians for an assumed heart attack; however, his condition quickly worsened.

[3][19] A private funeral for Ritter was held in Los Angeles on September 15, 2003, after which he was interred at Forest Lawn Memorial Park in Hollywood Hills.

[23] In 2008, at the Los Angeles County Superior Court, the jury concluded that the doctors who treated Ritter the day he died were not negligent and thus were not responsible for his death.

New male characters, played by James Garner and David Spade, were later added to the main cast as Ritter's replacements.

Four days after Ritter's death, Nick at Nite ran an all-night Three's Company marathon dedicated to his memory.

[29] In 2004, Ritter was posthumously given an Emmy nomination for playing Paul Hennessy in 8 Simple Rules... for Dating My Teenage Daughter but lost to Kelsey Grammer for his performances as the title character of Frasier.

[30] Ritter's final films, Bad Santa and Clifford's Really Big Movie, along with a Season 4 episode of Scrubs (his character in this series died, as well), the Season 8 King of the Hill episode "Stressed for Success" (in which he played music teacher Eugene Grandy) and Stanley's Dinosaur Round-Up (in which he played Great Uncle Stew) were all dedicated to his memory.