Born in the mountain town of Petrópolis, Brazil to Italian engineer Francesco Santoro and Brazilian artist Maria Jose, Santoro spent his childhood in Petrópolis where he studied at the Colégio Aplicação. Santoro later moved to Rio de Janeiro to attend the Pontifícia Universidade Católica as a marketing and advertising major. Interested in acting since childhood, Santoro became a part of Rio's street theater scene while studying at the university. With his natural charm and good looks, the teenaged Santoro quickly landed a small role on the Brazilian soap opera, "Olho no Olho" (1993). The following year, he landed another part, this time on the primetime soap, "Pátria Minha" (1994). With a handful of television credits to his name, Santoro landed his first major role in 1996. Cast as the lead male character on the soap opera, "O Amor Está no Ar" (1996), he was soon forced to leave school due to the show's intense shooting schedule. Taking his acting career more seriously, later that year, Santoro went on to make his film debut in the acclaimed short, "Depois do Escuro" (1996). Garnering attention for his role as Frei Malthus in the miniseries "Hilda Furacão" (1998), Santoro began to display his true gifts and consequently, began receiving serious critical acclaim. In 1999, Santoro voiced the title character in the Brazilian release of the animated film "Stuart Little" (a role he reprised in 2002 with the Brazilian release of "Stuart Little 2"). Landing his first major feature role in the Brazilian film, "Bicho de Sete Cabeças" (2001), Santoro portrayed a young man unjustly sent to a psychiatric ward. After receiving critical praise and a number of awards for his performance in the film, Santoro went on to appear in "Abril Despedaçado" (2001) the same year. Santoro followed up his hot streak by turning in another critically acclaimed performance as a transsexual prisoner in Hector Babenco's "Carandiru" (2003). In 2003, Hollywood began to take notice of Santoro as well. Cast in a television adaptation of Tennessee Williams' "The Roman Spring of Mrs. Stone" (2003), Santoro acted alongside such heavyweights as Helen Mirren and Anne Bancroft. He quickly landed small roles in the poorly received sequel to the 2000 hit, "Charlie's Angels - the dismal "Charlie's Angels: Full Throttle" (2003), as well as the British romantic comedy "Love Actually" (2003). In perhaps his most notable role up until that time, in 2004, Santoro was picked by "Moulin Rouge" (2001) director Baz Luhrmann to star opposite his muse, Nicole Kidman, in a two-minute ad for the high-end Chanel perfume. Audiences could not help but notice the bespectacled hunk, pining away for Kidman's actress who flees her premiere to shack up briefly with the bohemian artist in his roof-top apartment. The fact that the ad was as long as it was, also made an impression.Back to his homeland, Santoro went on to star in the romantic comedy "A Dona da História" (2004), the mini-series "Hoje É Dia de Maria" (2005) and "Os Desafinados" (2006). Proving once again, his international appeal, Santoro landed two key roles in 2006 which cast the American spotlight on firmly on him as never before. Portraying Paulo, a survivor of the ill-fated Oceanic Flight 815, Santoro joined the cast of ABC's hit drama "Lost" (2004-10) during its third season. Any addition to this beloved cast was met with an immediate interest from diehard "Lost" fans, who began checking out Santoro's past résumé as soon as his casting was announced. Scoring a double whammy for fan boys - not his usual fan demographic - Santoro landed the role of the megalomaniacal, over-the-top Persion King Xerxes in the highly anticipated feature adaptation of Frank Miller's "300" (2007). Enjoying his newfound international recognition, Santoro moved on to a series of motion picture projects, working alongside several of Hollywood's most respected talent. He played an unscrupulous MMA fight promoter in writer-director David Mamet's Kurosawa-esque neo-noir "Redbelt" (2008). That same year, he was seen as Raúl Castro, brother of Fidel, in the epic-length historical biopic "Che" (2008). Shown in two separate parts internationally, the massive undertaking was directed by Steven Soderbergh and starred Benico Del Toro in the title role of the controversial Marxist revolutionary. In a change of pace, he took on a smaller role as the trophy boyfriend of a gay con man (Jim Carrey) in the dark romantic-comedy "I Love You, Phillip Morris" (2009), co-starring Ewan McGregor in the eponymous role of Carrey's one true love. After a year-long return to Brazilian television work, Santoro was seen alongside an impressive cast in writer-director Roland Joffe's historical docudrama "There Be Dragons" (2011) and heard as the voice of a kind-hearted ornithologist in the animated feature "Rio" (2011).