Lowell Mather is a long time resident of Nantucket, whose family has lived on the island for five generations. Described as dim and eccentric mechanic/handyman, he works at the airport and is available to everyone when repairs are needed. His mentor was local handyman Weeve Gilroy, who died in 1993 at the age of 90. They had worked together to rebuild and restore an old biplane together. It was his shop teacher, Mr. Connolly, who inspired him to become a mechanic. Unfortunately, the guy was a "freakin' psycho!." Lowell ended up graduating from M.I.T. (Murray's Institute of Tools), but it took him two weeks to graduate. If he had another fifty-nine dollars, he could have become Doctor Mather. He later started working as a mechanic at Tom Nevers Field, but later, he seems to be working directly for Hoe Hackett and Roy Biggins. Lowell claims that while he is not an orphan, his brother is. He was married to a woman named Bunny with whom he had several children, but they divorced when Lowell learned that Bunny was sleeping around.
Lowell has a large and eccentric family. He has a sister Trina who has twins and a brother he calls an orphan. He had an Uncle Lowell who vanished and was later found in the well behind his house. His Aunt Frita could do an excellent chicken impersonation. Lowell claims to have actually found an egg once when she got out of her chair. His Uncle Willy lost his nose in an industrial accident. When his uncle died, Lowell rented a tuxedo for him to be buried in. He paid $112.50 per week until Fay Cochran made him go to the store and ask for a refund. He mentions his Cousin Bevo a lot around the airport.
After his divorce, Lowell allowed Brian Hackett to borrow his boat for an evening, and Brian sunk it. Lowell was invited by Joe and Brian and stayed with them for a year, where Lowell revealed a surprising talent for cooking. After about a year, however, his eccentricities and quick temper became unbearable to the Hacketts, and they kicked him out to find his own place.
Eventually, Lowell is forced to leave Nantucket and enter the Witness Protection Program after witnessing a mob hit. Although it was hard for him to leave Nantucket and the people he knew all his life, Lowell decided he would prefer to go into hiding than let a guilty man get away scot-free, knowing he could murder again.
- Lowell has lived on Nantucket all of his life. As a child, he was once trapped in an icy lake for five hours. He was in an issue of Time magazine for it.
- His mother had a fling with communism back in the Fifties. His mom never came to pick him up after the first day of kindergarten. Although he was not an orphan, he claims to have a brother who was.
- He married Bunny. His proposal was "We've been screwing around long enough. Let's make this thing legal." He and Bunny had two children and lived on a houseboat until they separated because Bunny was sleeping with other men and eventually divorced.
- Lowell is a leg man, although he considers a woman's chest hair to be her sexiest body part.
- He says he once put a whole kitten in his mouth.
- He considers Tom Petty to be the handsomest man in the world.
- He confuses Dylan Thomas, Bob Dylan, Bob Denver and John Denver.
- He names his golf balls.
- According to Mather family tradition, he received a check for twenty-five thousand dollars when he turned thirty-one and a half. With the money he purchased a Wax Museum, but got his money back when the insurance covered it burning down. He called it "Lowell Mather's House o' Wax: The Waxiest Place on Earth" The fire resulted from sparks starting in the Dark Ages display. His business partner in the deal was named Knuckles.
- He almost always wears the same orange baseball cap. It means a lot to him. The first time he fixed a crank case was in that hat. The first time Lowell Jr. threw up was in that hat. And the first time he was hit in the head with a brick was in that hat.
- Although Lowell was often seen with the orange baseball cap, he would be hatless in places where it was blatantly rude to wear a hat indoors, such as church, a fancy restaurant or Joe and Helen's wedding.
- Lowell can speak fluent French.
- He says he's lived through several great fogs including: November of '82, April of '84, and August of '87.
- He thinks there are only 42 weeks in a year.
- He believes holes in the universe exist, and he calls them "cosmic potholes."
- He wonders if Mr. T is related to Mr. Coffee.
- Lowell owns a video camera.
- He likes sitting alone in the dark, calling it relaxing.
- He is allergic to ragweed, and if exposed to it he will start sneezing.
- His nicknames include: Slackass (by Roy)
- His last action prior to leaving Nantucket was to donate his signature orange ball cap to Joe and Brian for them to remember him by. Joe proceeded to hang the hat in the hanger, Lowell's former workshop, with a message saying not to touch it in honor of their departed friend.
- Though often perceived as an idiot, Lowell is actually very intelligent and given the right situation he can be very helpful. These characteristics are similar to a savant, meaning Lowell could possibly have a neurological disorder.
- Lowell may have possibly been attracted to Casey. This is evident when he kisses her twice. At one point, he refers to her as "dumpling".
- Lowell is heavily inspired by a "Cheers" character named Gordie Brown, who was also played by Thomas Haden Church who guest starred in "Death Takes a Holiday on Ice."