In film after film, Shah Rukh Khan has romanced the screen as the ultimate lover boy. As he turned 45 Tuesday, the unconventional looking youngster who took Bollywood by storm 18 years ago was set to blaze a new trail by turning superhero in "Ra.One".

Shah Rukh, who has over 60 films under his belt and millions of fans across the globe, enjoyed his birthday in Berlin where he is shooting for "Don 2".

"I have not had so much fun on my birthday before...learnt ripsticking...Duggu (Hrithik Roshan), Sussanne, Raveena and the gang of 'Don 2' partied, " he posted on his Twitter page. He also thanked all his Twitter fans "around the world" for making him "feel so special" on his birthday.

The actor is going for a image makeover with his home production "Ra.One".

"People like Shah Rukh like reinventing themselves. They like challenges and they like donning different characters. When you are 20-21, you can play a college lover boy easily but he understands that once you are above 35 or so, you can't just do the same thing, so he reinvents, " film critic Omar Qureshi told.

"He is very smart and he knows what works. I'm sure when he thought of doing a superhero thing he knew that it will work, " he added.

Shah Rukh made his film debut with "Deewana" in 1992. In the initial days, he essayed charaters with grey shades in "Baazigar", "Darr" and "Anjaam". But it was his dream role in "Dilwale Dulhania Le Jayenge" that got him a firm place in romantic sagas and turned him into the nation's heartthrob.

Later "Pardes", "Dil Toh Pagal Hai", "Kuch Kuch Hota Hai", "Dil Se", "Mohabbatein", "Kabhi Alvida Naa Kehna" and "Veer Zaara" helped him climb the ladder of superstardom swiftly.

With a string of hits, the superstar, also called King Khan, became a phenomenon that defies explanation. That didn't stop Shah Rukh, the son of a freedom fighter, from taking up unconventional roles in "Swades" and "Chak De" and earning praise from audiences and critics alike.

He also dabbled in production and television. The actor, who began his career with popular television serial "Fauji" in the late 1980, went on to host "Kaun Banega Crorepati" and "Kya Aap Panchvi Pass Se Tez Hain".

The actor, who has 13 Filmfare Awards and a Padma Shri, this year tried to be different by doing the issue-based "My Name Is Khan" which highlights prejudices against Mulsims after 9/11.

The year 2011 will see him both as don and superhero.

While "Don 2 - The Chase Continues" is a sequel to Farhan Akhtar's "Don" also starring Om Puri, Priyanka Chopra and Kunal Kapoor, "Ra.One" is a science fiction story where Shah Rukh will be seen as a superhero laden with extraordinary powers.

"'Ra.One' is a simple story of a father and a son. There have been a lot of movies and songs dedicated to mothers but unfortunately, fathers are ignored. I being a father myself and a part of cinema, decided to give them all some space through my film, " Shah Rukh said.

"The film is dedicated to all the fathers in the world. I hope this film will help bring fathers at the front and make me a hero in the eyes of my son, " he added.

The actor has two children - son Aryan, 13, and daughter Suhana, 10 - with wife Gauri Khan.

Shah Rukh is expected to do some daredevil stunts in "Ra.One", which is being directed by Anubhav Sinha and also stars Kareena Kapoor and Arjun Rampal. It is being produced under Shah Rukh's production banner, Red Chillies Entertainment.

Will the superhero avatar reinforce Shah Rukh's superstar status? Watch on.