stylistic:tone, quality:correction, structural:reformatting, information:filtering, structural:expansion
2000–2013: Resurgence and final roles

O'Toole's work in the next decade included Global Heresy (2002); The Final Curtain (2003); Bright Young Things (2003); Hitler: The Rise of Evil (2003) for TV, as Paul von Hindenburg; and Imperium: Augustus (2004) as Augustus Caesar. In 2004, he played King Priam in Troy. In 2005, he appeared on television as the older version of legendary 18th century Italian adventurer Giacomo Casanova in the BBC drama serial Casanova. The younger Casanova, seen for most of the action, was played by David Tennant, who had to wear contact lenses to match his brown eyes to O'Toole's blue. He followed it with a role in Lassie (2005).

O'Toole was once again nominated for the Best Actor Academy Award for his portrayal of Maurice in the 2006 film Venus, directed by Roger Michell, his eighth such nomination. He was in One Night with the King (2007) and co-starred in the Pixar animated film Ratatouille (2007), an animated film about a rat with dreams of becoming the greatest chef in Paris, as Anton Ego, a food critic. He had a small role in Stardust (2007). He also appeared in the second season of Showtime 's drama series The Tudors (2008), portraying Pope Paul III, who excommunicates King Henry VIII from the church; an act which leads to a showdown between the two men in seven of the ten episodes. Also in 2008, he starred alongside Jeremy Northam and Sam Neill in the New Zealand/British film Dean Spanley, based on an Alan Sharp adaptation of Irish author Lord Dunsany's short novel, My Talks with Dean Spanley.

He was in Thomas Kinkade's Christmas Cottage (2008); and Iron Road (2009), a Canadian-Chinese miniseries. O'Toole's final performances came in Eldorado (2012) and For Greater Glory: The True Story of Cristiada (2012). On 10 July 2012, O'Toole released a statement announcing his retirement from acting. A number of films were released after his retirement and death: Decline of an Empire (2013), as Gallus; and Diamond Cartel (2017).