Paul Giamatti would just like to put it out there that maybe he doesn’t always have to play such a motormouth.It might be nice, just to shake things up a bit, if he could portray someone more likely to express themselves nonverbally — a taciturn horse breeder with an anguished past, say, or a world-class safecracker with shrapnel-related vocal cord injuries.“Please, don’t make me talk so much,” he said recently, in a low register, his hangdog eyes pleading with the universe.Giamatti watchers may have a hard time imagining the actor tongue-tied. He is one of cinema’s great talkers, often cited for dazzling flights of oratory. Think of Miles’s profane rebuke of merlot in “Sideways” (2004), or the founding father flogging the virtues of independence in “John Adams” (2008) or the brash boxing manager Joe Gould in “Cinderella Man” (2005). For Giamatti to yearn for fewer lines of dialogue might sound like a Formula 1 car pining for a bus route.His latest role, as Paul Hunham in “The Holdovers” — a solitary and cantankerous New England boarding-school teacher saddled with babysitting duty over Christmas break — adds a number of memorable monologues to the actor’s oeuvre. But Giamatti also imbues the character with a deep well of melancholy and thinly disguised tenderness, traits that tend to reveal themselves in wordless, physical gestures: a crumpling of the chin, a narrowing of one eye.“There are close-ups where you can see not only his transition from one thought to the next, but all of the little micro-thoughts that happen in between,” said Alexander Payne, the director of “The Holdovers,” who reteamed with Giamatti nearly 20 years after “Sideways.” “You could hire him to play the Hunchback of Notre Dame and he’d do a great job with it.”The real Giamatti, as encountered last month during an interview in Beverly Hills, is soft-spoken, gentle-mannered and contemplative, with a habit of gazing off into the distance when he needs to collect a thought. If you didn’t keep up with “Billions,” Giamatti’s workhorse Showtime drama that ended in the fall after seven seasons, his hair is whiter than you might remember, as if Santa Claus had a brother with a humanities degree.Giamatti is often mistakenly presumed to be similar to his characters, which is both a compliment and a nuisance. Payne is convinced that the actor didn’t receive an Oscar nomination for “Sideways” (his co-stars Thomas Haden Church and Virginia Madsen were nominated in the supporting categories) because he made it look too easy. In real life, let it be known, Giamatti is not terribly interested in wine and knows little about it, much to the dismay of fans who approach him in restaurants.Aside from a shared interest in the arcana of the Roman Empire, he has few things in common with his character in “The Holdovers” — an antiquities teacher and campus ogre with an impaired eye and a skin condition that makes him smell like fish.Yet Giamatti found himself strangely invested in the role. Both of his parents were teachers (his father, A. Bartlett Giamatti, was the president of Yale and later the commissioner of Major League Baseball), and he graduated from a prep school similar to the one depicted in the movie. More so than for any role he can recall, he got lost in the character, allowing his own memories and experiences to color his performance.After playing so many loquacious characters, Giamatti would love to take on a taciturn sort: “Please, don’t make me talk so much.”Sinna Nasseri for The New York Times“It was more unconscious than normal, which was a little alarming because I almost felt at times like I wasn’t working hard enough, like I was being lazy,” Giamatti said. “Even when I watched it, it was weird. I kept looking on and thinking, Is that what I was doing?”Giamatti was born and raised in Connecticut and attended Yale for both his undergraduate degree and masters of fine arts, in English literature and drama. Although he quickly dispensed with the idea of following his parents into academia, he has always been a voracious reader with a deep interest in science fiction, history, philosophy and mysticism. On “Chinwag,” Giamatti’s podcast, started earlier this year with Stephen Asma, a philosophy professor and author, the actor peppers friends and experts with questions about obscure historical figures and the paranormal: ghosts, U.F.O.s, Hollow Earth theory, ancient Egypt.Asma befriended Giamatti during the pandemic (the actor emailed him, out of the blue, to compliment him on an online lecture he’d given about the science of imagination), and said they had spent two hours during their first conversation discussing the little-known 18th-century Swedish theologian Emanuel Swedenborg.“Every wall of every room in his apartment has bookshelves filled with books, multiple levels deep,” Asma said. “He reads more than most English professors I know, but he wears it lightly.”In both his life and his work, Giamatti has always been drawn to characters on the margins. He is the rare baseball fan more interested in the umpires than the players. (“You’re a hugely important part of the game, and yet you’re outside of it — what is that like?”)“There are close-ups where you can see not only his transition from one thought to the next, but all of the little micro-thoughts that happen in between,” said Alexander Payne, director of “The Holdovers.”Sinna Nasseri for The New York TimesEven in supporting roles — a coldblooded slave trader in “12 Years a Slave,” a duplicitous music manager in “Straight Outta Compton” — his presence turns up the volume of humanity onscreen.When he is preparing for a part, Giamatti reads and rereads the script numerous times (he is not generally a fan of improvisation), making inferences about how the character might present in three dimensions. He often looks for ways to transform himself physically, a task for which his regular-joe facade has proved handy.“You can dress me as a short-order cook, or as a butler, or as the president of the United States in the 18th century, and I kind of look like I should wear the clothes,” he said.For “The Holdovers,” in which his character gradually forms a bond with a bright but troubled student (the newcomer Dominic Sessa) and the head of the school’s cafeteria (Da’Vine Joy Randolph), Giamatti grew a handlebar mustache and wore a toggle jacket inspired by a similar one of his father’s.But the person he most found himself channeling, the man he sees when he watches the film now, is a biology teacher from his own prep school, Choate Rosemary Hall: a sarcastic, “pasty, comb-over man” who seemed lonely and smelled like an ashtray and a martini.As a student, Giamatti didn’t think much about the man, and the two almost never exchanged words. But one day, late in the school year, after a test on which he had performed uncharacteristically poorly, the teacher stopped by Giamatti’s desk.“He handed me back the test and said, ‘You usually do really good on these, what happened?’” Giamatti recalled. “I was like 15 and just shrugged: ‘I don’t know, man.’ But the guy stayed there and he looked me in the eye and asked, ‘Is everything OK?’”Giamatti, feeling awkward, said that it was, and they never discussed it again. But the fact that the teacher — someone he had effectively considered a stranger, or worse — not only knew him well enough to suspect something was wrong, but cared enough to ask, has always stayed with him.“It took me by surprise,” Giamatti said. “He actually gave a [expletive] about us.” More