Boomhauer (voiced by Mike Judge) is a character in the animated series King of the Hill. Hank Hill, Dale Gribble, and Bill Dauterive are his neighbors, and the four have been close friends since childhood. "Boomhauer" appears to be his last name, since Bobby often calls him "Mr. Boomhauer". Boomhauer spends most of his spare time drinking Alamo Beer with Hank, Dale and Bill in the alley behind Hank’s house. In the episode "Luanne Virgin 2.0," Boomhauer is a limo driver. It is mentioned in one episode that he is an electrician on worker’s compensation. Another reveals that his parents are rich after having won the lottery, and a third implies that Boomhauer receives favors from the various women with whom he sleeps. In an episode where he must hold suicide watch over Bill, he complains that his life is now "Work, Bill, work, Bill", proving he has a steady job. On the FX Networks website that shows King of the Hill, it says that “Boomhauer likes Seinfeld...‘dat show about nothin’ and he works in a deafeningly loud factory that makes barbed wire.” His primary pursuits are fast cars and loose women. In the episode “It’s Not Easy Being Green,” it is revealed that in high school, Boomhauer had a beloved cherry-red Ford Mustang named Sally. Bill, Dale, and Hank took the car on a late-night joyride and, through a series of mishaps (notably Dale's inability to drive a car with manual transmission), Sally ended up at the bottom of the Arlen quarry. Boomhauer believed that the car had been stolen until the quarry was drained and it was hauled out of the water with his friends' letterman jackets inside. He currently drives a 1968 Dodge Coronet.

Boomhauer’s speech patterns are nearly incomprehensible to the untrained audience and serve as a recurring theme. He mumbles and invariably uses the words "dang ol’" as an all-purpose adjective, sometimes several times in a single sentence. He also uses the phrases "I tell ya what" and "man" frequently. His poor enunciation and heavy Southern accent sometimes lead to misunderstandings about his mental capacity. In one episode, he was admitted to a mental hospital in downtown Houston after he drifted in on the river in a tube and was found in his Speedo, sunburned, drunk, dehydrated, and babbling incoherently. All of the regular characters on the show understand most of what he says. There is a recurring joke in which Hank occasionally cannot understand Boomhauer due to extenuating circumstances such as a bad telephone connection or an echo. Often, the closed caption texts of Boomhauer’s mumblings are clearer than his spoken words. An example of a typical line of dialog: Boomhauer’s speech is satirical of “rednecks” using phrases such as "dang ol'" “dad gum” and “yeah, man talkin’ ’bout.” Nevertheless, he sings clearly, as evidenced by his rendition of “Blue Moon of Kentucky” in Episode 6.9 (“The Bluegrass Is Always Greener”). The singing was done by country star Vince Gill. In “A Fire Fighting We Will Go,” when it shows his account of an incident, he is the only one who speaks normally while everyone else speaks with his mumbling. Mike Judge has stated that the inspiration for Boomhauer’s voice came from a message left on his answering machine by an irate viewer of Beavis & Butt-Head. Season 1 episode "Hank's Got the Willies" cleverly shows Boomhauer and the famously-incomprehensible Bob Dylan conversing with one another.

Boomhauer has had four relatives that have appeared on the show. His mother, his “Meemaw” (a Southern term for grandmother), and his father, Dr. Boomhauer. Mrs. Boomhauer and Meemaw both have the same speaking patterns as Boomhauer; Dr. Boomhauer does not speak. The fourth family member is Boomhauer’s sleazy brother, Patch, who was voiced by Brad Pitt in his only appearance. Patch was preparing to marry Boomhauer’s ex-girlfriend, Katherine (Laura Dern). The wedding did not take place because Katherine learned of her fiancé’s promiscuous behavior, and possibly because she still harbored feelings for Boomhauer. It was revealed in this episode when Katherine went off to college, Boomhauer spent two days sitting in his hot tub, nursing a broken heart.

Boomhauer is apparently highly intelligent and often gives advice to his friends. Once after giving advice to Bobby Hill, Bobby replied by saying “I can see why my dad's always quoting you Mr. Boomhauer.” In another episode, he mentioned that his mother wanted him to become an electrical engineer. Given the opportunity, Boomhauer will also demonstrate that he is, in fact, quite cultured. In "Ceci N’Est Pas Une King of the Hill" Hank Hill makes remarks about art that deride it's modern state provoking Boomhauer to call him ignorant makes a series of remarks going as far as to cite Dadaism and the famed Marcel Duchamp work Fountain.

Although considered something of a playboy by his neighbors, he has trouble getting over break-ups. When he met a jogger whom Bill lusted after, he spent many days (and nights) with her, before he made up the courage to ask her to marry him. To his horror, she had been sleeping with another man and only dated him for the sex. Adding insult to injury, she admitted that she hadn't understood much of what he'd said since they met and mistakenly referred to him as "Boomhauser". Crushed, Boomhauer went speeding down the street with “Barracuda” playing, crying in sadness. He spent the next few days trying to call her back to beg her to come home, and then trying to find another woman, with no success. Bill, a veteran at getting dumped, helped his friend get over the jogger and back on his feet by giving him a motivating and uplifting speech.

Boomhauer favors animal-print bikini briefs, which has been observed a few times in the show when he’s appeared without his blue jeans. In an episode where Hank, Bill, Dale, and Boomhauer were stuck in the water because they jumped off a boat, Boomhauer confessed that he dyes his hair ("Hank's on Board").

He was once one of the best surfers in Corpus Christi. He also plays Scruggs style banjo in a bluegrass band with Barry Hermann. He owns a limousine, which has not been seen, but was mentioned when Luanne Platter was planning her wedding to Rhett Van Der Graaf.