Schell's agent, Patricia Baumbauer, said Saturday he died overnight at a hospital in the Austrian city of Innsbruck following a "sudden illness."
It was only his second Hollywood role, as defense attorney Hans Rolfe in Stanley Kramer's classic "Judgment at Nuremberg," that earned him wide international acclaim. Schell's impassioned but unsuccessful defense of four Nazi judges on trial for sentencing innocent victims to death won him the 1961 Academy Award for best actor. Schell had first played Rolfe in a 1959 episode of the television program "Playhouse 90."
Despite being type-cast for numerous Nazi-era films, Schell's acting performances in the mid-1970s also won him renewed popular acclaim, earning him a best actor Oscar nomination for "The Man in the Glass Booth" and a supporting actor nomination for his performance alongside Jane Fonda, Vanessa Redgrave and Jason Robards in "Julia."
Austrian Cabinet minister Josef Ostermayer described Schell as one of "the greatest actors in the German-speaking world," the Austria Press Agency reported.
The son of Swiss playwright Hermann Ferdinand Schell and Austrian stage actress Noe von Nordberg, Schell was born in Vienna on Dec. 8, 1930 and raised in Switzerland after his family fled Germany's annexation of his homeland.
Schell followed in the footsteps of his older sister Maria and brother Carl, making his stage debut in 1952. He then appeared in a number of German films before relocating to Hollywood in 1958.
By then, Maria Schell was already an international film star, winning the best actress award at the 1954 Cannes Film Festival for her performance in "The Last Bridge."
Maximilian made his Hollywood debut in Edward Dmytryk's "The Young Lions," a World War II drama starring Marlon Brando, Montgomery Clift and Dean Martin.
Schell later worked as a producer, starting with an adaptation of Franz Kafka's "The Castle," and as a director.
"First Love," adapted from the Ivan Turgenev novella—which Schell wrote, produced, directed and starred in—was nominated for an Oscar in the best foreign film category in 1970. "The Pedestrian," another movie under Schell's direction and production, received the same nomination three years later.
Perhaps Schell's most significant film as a director was his 1984 documentary on Marlene Dietrich, "Marlene," which was nominated for a best documentary Oscar. Dietrich allowed herself to be recorded but refused to be filmed, bringing out the most in Schell's talent to penetrate images and uncover reality.
Schell was also a highly successful concert pianist and conductor, performing with such luminaries as Claudio Abbado and Leonard Bernstein, and with orchestras in Berlin and Vienna.
In the 1990s, Schell made appearances in films including "The Freshman," "Telling Lies in America" and "Deep Impact." In 1992, he received a Golden Globe for his supporting role as Lenin alongside Robert Duvall in the 1992 HBO miniseries "Stalin".
In a documentary entitled "My Sister Maria," Schell portrayed his loving relationship with his sister, who died in 2005.