Obama
Although Barack Obama has often referred to his Christian faith, only one-third of Americans identified the U.S. president as a Christian in a recent poll. Reuters

Actor Will Smith, recently referred to President Barack Obama by his first name in an interview with BBC Radio 1.

The actor was recalling a story about how he and his wife, Jada Pinkett Smith, and their two children went to the White House, and throughout the interview he referred to the U.S. president as Barack. He also referred to the First Lady and her two daughters by their first names.

The level of informality makes us wonder, which other celebrities get to call the president by his first name?

Here's a look at the possibilities.

George Clooney

We're pretty sure George Clooney and Obama are on a first-name basis. Obama certainly calls the actor by his first name. We raised a lot of money because people love George, the president said at a re-election fundraiser the actor hosted, TMZ reported. They like me. They love George. The two men have even played basketball together, according to Clooney's latest squeeze, Stacy Keibler (she referred to the president as Obama, according to an Us Weekly report).

Eva Longoria

Eva Longoria is the co-chair of the Obama Re-Election Campaign. She's referred to him as President Obama in interviews, but can probably do the whole first-name thing in less formal settings.

George Lopez

Lopez helped the Obama campaign the first-time around. I'm proud to call him a friend, the funny man said of the president in a red-carpet interview with Hollyscoop.com. He did refer to Obama as Senator Obama in an interview with a Houston news station in 2008, when the future president was still on the campaign trail.

Brad Pitt

The president and Brad Pitt are, in fact, related. The New England Historic Genealogical Society revealed in 2008 that the president and the hunky actor are distant cousins, the Huffington Post reported, but while it's possible they are on a first-name basis thanks to the actor's and Angelina Jolie's humanitarian work, we doubt they meet up at family reunions.

Oprah Winfrey

She referred to the president as Barack Obama in an interview with CNN earlier this year. She was discussing her past endorsement of the president. There's not a person in the world who doesn't know who Barack Obama is, she told CNN. Winfrey's famous endorsement of Obama in the first election was seen by political analysts as a big boost to his campaign, so we're sure that she and the president and his family are on pretty friendly terms.