Now that Justin Bieber has gone ahead and shown his six pack abs on Instagram, we thought of assembling a list of Hollywood actors who have the abs to die for. Let's take a look at the Hollywood hunks who look irresistibly hot when shirt less:

Justin Bieber: Trying to break his teen singer image, Bieber has recently acquired six pack abs. The singer is so smitten by his new body that he couldn't resist from showing his body on a social media site. Many reporters say that Bieber is gaining mature looks to impress is his ex, Selena Gomez.

Liam Hemsworth: The star of "Hunger Games: Catching Fire", better known as Miley Cyrus's ex has a body to die for. When Miley was still dating Liam, she had this to say about Liam Hemsworth's body, "The other day, I turned on the pool heater and it was steaming, and he walked outside and took off his clothes and jumped in the pool. I was like, 'I'm gonna faint - the hottest guy of my life is in a steaming pool." We wonder if Miley miss those abs.

Zac Efron: Efron is not a newbie when it comes to going shirtless. The star has taken off his shirt many times for a film shoot and indeed his fit body has set the temperature soaring. Efron was recently reported to be dating Nicki Minaj and had a short stint in a rehab.

Robert Pattinson: Who can forget Pattinson getting under the sheets with a French model showing his six pack abs for the recent Christian Dior Ad?Pattinson has one of the hottest bodies in the Hollywood and supposedly, Robert spends most of his time in gym when not shooting or dating girls.

Ian Somerholder: Nina Dobrev's ex is another hottie in tinsel town. After Charlie Hunman's walking out from 'Fifty Shades of Grey,' it is rumored that Ian Somerholder can get the coveted role of Christian Grey. Would his hot abs get him the role?

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