Hollywood's full of drama, excitement and change. Aside from celebrities who enjoy making constant changes on their relationship status, another thing they love to change about themselves would be their hairstyle.

"Drastic" wouldn't be the word for Katy Perry's new hair, rather "refreshing." The 27-year-old singer showed off her new hairstyle at the benefit celebration Saturday. Ironically, Katy Perry embodied the benefits' theme of "Change Begins Within" by showcasing her blonde-pink short hair.

Before Perry's hair transformation came quite a few others. Emma Watson leads the charts for the most drastic celebrity hair makeover with her pixie cut.

Being in the "Harry Potter" franchise for over 10 years, Watson was not allowed to change her hairstyle simply to fit for her role as the bushy-haired Hermione Granger. July marked the end of the Harry Potter franchise which in turn also marked the end of the Hermione Granger hair.

Watson wowed her fans with her pixie cut hair on the premiere of "Harry Potter and the Deathly Hallows Part 2." Yet, her haircut did not mark the end of her acting career. It did quite the opposite with Watson being cast off into more roles. "Beauty & the Beast," "Perks of Being a Wallflower" and the most recently, "My Week with Marilyn," are just a few films fans of Watson should watch out for.

Aside from being a hit on the music charts, Taylor Swift is also a hit on the red carpet. The country crooner is known for her curly blonde locks but fans still agree she'd rock the straight look better.

"Got a haircut," tweeted the singer along with a picture of her new 'do. She'd definitely rock the straight look better and everyone knows the look makes her more mature.

Among a few others who have had extreme hair makeovers this year is Katherine Heigl. The blonde beauty went brunette for just a few months before reverting back to blonde. Femme fatale Megan Fox also had a hair makeover from coloring her dark frown roots to bombshell black.

The singer Solange Knowles not only made a hit with her music like Swift but with her hair as well. First breaking into the scene with long, straight and black locks to completely shaving off her hair. Finally, her hair change ended by growing her hair back to a curly afro which made quite a statement.

Scarlett Johansson made a scene not only with her racy nude photos scattered over the Web but with her drastic hairdo as well. The redhead switched to the strawberry blonde look. It still didn't win her back former hubby Ryan Reynolds.

Kristen Stewart rocks the charts with her messy updo. From her teen queen look of brown hair to the rocker look of short and messy black crop for her role in "The Runaways," until finally growing it back to her curly black locks.

Eva Mendes could be included in the list, but her "Amy Winehouse" hairdo was simply part of her role in the movie "Holly Motors." Still, the actress managed to look hot in the beehive red hair. Could be another reason how she managed to snag equally hot Ryan Gosling.

With the New Year just days away, Hollywood celebrities are sure to be changing more than their looks.

Katy Perry announces the nominees for Album of the Year at The Grammy Nominations Concert Live - Countdown to the Music's Biggest Night event at Nokia theatre in Los Angeles November 30, 2011. The 54th annual Grammy Awards will be presented February 12, 2012 in Los Angeles.

Cast member Emma Watson arrives for the European premiere of "My Week With Marilyn" in London November 20, 2011.

Singer Taylor Swift arrives at the 2011 American Music Awards in Los Angeles November 20, 2011.

Actress Katherine Heigl, ShoWest Female Star of the Year, poses before the awards ceremony at the Paris Las Vegas during ShoWest, the official convention of the National Association of Theatre Owners, in Las Vegas, Nevada March 18, 2010.

Actress Megan Fox arrives on the red carpet for the film "Friends With Kids" during the 36th Toronto International Film Festival (TIFF) in Toronto, September 9, 2011. TIFF runs from September 8 to18.

Singer Solange Knowles arrives at ELLE magazine's second annual Women in Music event in Hollywood, California April 11, 2011.

Actress Scarlett Johansson poses at the 5th annual Spike TV's Guys Choice awards in Culver City, California June 4, 2011. REUTERS/Mario Anzuoni

Actress Kristen Stewart attends her hand and footprint ceremony at the Grauman's Chinese Theatre in Hollywood, California November 3, 2011.

Actress Eva Mendes poses during arrivals for the Academy of Motion Picture Arts & Sciences Tribute to Sophia Loren in Beverly Hills, California, May 4, 2011.