In his upcoming film, the 1930s period drama "Water for Elephants," based on Sara Gruen's best-selling novel of the same name, Robert Pattinson begins to show new depth and range as an actor. Plus, his hair looks really, really different.

Much like his career, RPattz's hair is evolving. So, when MTV News sat down with the star for "MTV First: Robert Pattinson," it seemed like the perfect time to reflect on the diverse coifs that have sent his follicle-obsessed fans into a frenzy.

From his "Twilight"-appropriate 'dos such as "The Wavy Forest" and "The Cullen Pouf" to the self-explanatory "Windswept 'What the F---' " to the more subdued and serious looks like "Controlled Chaos" and "Clean & Cut but Hold the Shave," Pattinson took a trip down memory lane of the many haircuts he's rocked.

"I always like ... the 'Forest' thing," he said. Turns out, that particular hair style carried him through what he describes as the "unemployable" phase of his career. While attending the Los Angeles premiere of "Harry Potter and the Order of the Phoenix" in 2007, Pattinson admitted to looking rather, well, unkempt.

"I walked down Hollywood Boulevard to Grauman's [Chinese Theater] and had to walk through the crowd and stuff," recalled the 24-year-old star who was not yet famous, adding, "I was so hungover and so bloated, and some of the pictures are just so funny. It literally looks like someone just found a homeless person and just put them on [the red carpet]. ... It was so ridiculous."

So, what is it that helps the star maintain that tousled, albeit sometimes homeless-looking hair? Courtesy of his "Twilight" co-star Ashley Greene, we asked RPattz what brand of shampoo he uses: "I use dog shampoo," he joked. In reality, he, like so many other sexy slacker types before him, simply uses, "Whatever is around."

But, the question remained: Would Pattinson ever rock the oh-so-sought-after Justin Bieber 'do? Despite rumors that he and his fellow heartthrob had discussed their hair together ("I never met this guy!" Pattinson told MTV), the actor was somewhat willing to take on the side-swept style. After laughing about the idea of sporting "The Bieber," RPattz quipped that instead he'd wear "a Bieber hat."

Which Robert Pattinson hairstyle is your favorite? Sound off in the comments below!

Check out everything we've got on "Water for Elephants."

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