'Iron Man' Star Robert Downey Jr Turns 51, Find Out What His Debut Role Was On His Dad's Film!

There is no doubt that many children or adults love Iron Man. The self-proclaimed genius, billionaire, playboy and philanthropist superhero is one of the most popular "Avengers." Did you know that the man behind the mask just celebrated his birthday?

Robert Downey Jr. a.k.a Tony Stark or Iron Man turned 51 on April 4. At his age, Downey Jr. has gone through ups and downs, but his success and transformation is one that would impress many.

According to Forbes, Robert Downey Jr. is the world's highest paid actor in 2015. Meanwhile, Variety reported that for five years since 1996, the "Sherlock Holmes" star experienced drug arrests and high-profile firing because his track record showed that getting a project done was impossible. It was quite a tough time for the "Iron Man" star.

In 2003, Mel Gibson gave Robert Downey Jr. another opportunity in "The Singing Detective," which paved the way for his career rebound. He underwent a personal rehab and has grown to be a new man and his career blossomed.

In 2008, Robert Downey Jr. cemented his return when he starred in the highly successful franchise "Iron Man" and "Tropic Thunder." After a year, he wowed the audience with "Sherlock Holmes." His success continues, which speaks why he was the highest paid actor last year.

But did you know how Robert Downey Jr. started his acting career? Per the report, the popular actor debuts his acting career by playing as a dog in "Pound" a film directed by Robert Downey Sr., his dad. Richard Gold criticized the film describing it as "unfunny allegory."

"The film's one funny sequence has nothing to do with anything: everybody just tweedles around in ballet costumes to a cheerfully obscene rock tune," Gold said. Robert Downey Jr. also appeared on his father's "Greaser's Palace" film. His big break came in 1992 when he starred in "Chaplin."

The director was all praises to his performance saying, it was a "miraculous, one of the most staggering performances I've seen in decades." Fans who saw the film were also impressed with the actor's performance.

Life was indeed a roller coaster ride for Robert Downey Jr. and we're glad that he is at the top again. Happy birthday Iron Man!