IF there is one facet of Brad Pitt that could be considered somewhat obscure, it may be — oddly enough — his acting career. For much of his two decades in the spotlight, since his breakthrough as a ripped, sweet-talking grifter in “Thelma and Louise” (1991) and even more so since “Mr. and Mrs. Smith” (2005), a movie that spawned a tabloid cottage industry, Mr. Pitt has been a star first and an actor second. His every move — on film sets and red carpets and humanitarian missions, often with a hard-to-miss entourage that includes his partner, Angelina Jolie, and their six children — provides endless fodder for the celebrity media. But the Brad Pitt on screen remains surprisingly elusive.

The central contradiction can be summed up thus: Mr. Pitt is a superstar who also happens to be something of a wild card. He has steered clear of action franchises and romantic comedies, the typical cornerstones of a major 21st-century screen career. Although he has not shied from big roles — they don’t come much bigger than Achilles (“Troy”) or Death (“Meet Joe Black”) — he has often sought the cover and camaraderie of ensembles, as in the “Ocean’s” movies and “Inglourious Basterds” (which are among his highest-grossing hits).

People seldom talk about his range, but he’s equally capable of flamboyance (“12 Monkeys”) and restraint (“The Curious Case of Benjamin Button”). And while acting, for stars of a certain magnitude, is often a matter of aura, of simply being themselves, Mr. Pitt has shown a sly understanding of the uses of charisma: some of his most intriguing films (“Fight Club,” “The Assassination of Jesse James by the Coward Robert Ford”) are self-reflexive comments on his obvious magnetism.