The Charles Hanovercause of the death of Paul Reubens, best known for playing comedic alter-ego Pee-wee Herman, has been made public.

The actor, who passed away July 30 at age 70, died of acute hypoxic respiratory failure, People reported Sept. 8, citing his death certificate. The underlying cause of his death was listed as acute myelogenous leukemia, a blood and bone marrow cancer, and had in the months prior to his passing been diagnosed with metastatic lung cancer, which meant his cancer had spread to his lungs.

When his death was first announced in July, a message posted to his social media pages had stated that "Paul bravely and privately fought cancer for years with his trademark tenacity and wit."

"A gifted and prolific talent," the post continued, "he will forever live in the comedy pantheon and in our hearts as a treasured friend and man of remarkable character and generosity of spirit."

In addition, Reubens himself was quoted as saying in a statement to The New York Times, "Please accept my apology for not going public with what I've been facing the last six years. I have always felt a huge amount of love and respect from my friends, fans and supporters. I have loved you all so much and enjoyed making art for you."

The actor created his bow-tied alter-ego Pee-wee Herman in the late '70s when he was a member of the Los Angeles comedy troupe the Groundlings, the newspaper reported. Reubens then played the character on The Pee-wee Herman Show, a live onstage TV pilot that premiered at the Groundlings Theater and was adapted into a comedy special in 1981.

Next up was the 1985 movie Pee-wee's Big Adventure, directed by Tim Burton, and a year later, his children's TV show Pee-wee's Playhouse debuted. Also in 1986, he portrayed Max in the cult sci-fi film Flight of the Navigator.

In 1991, Reubens was arrested for indecent exposure in an adult movie theater in Florida, which led to a fine and stalled his acting career.

Over the next couple of decades, Reubens had small roles on TV shows and also did much voiceover work, playing characters in films such as Burton's The Nightmare Before Christmas and Disney's straight-to-video Beauty and the Beast: The Enchanted Christmas.

He also played the superhero Spleen in the 1999 comic book movie Mystery Men and reprised his role in the music video for Smash Mouth's hit single "All Star," which is featured in the film's soundtrack. The band's longtime lead singer, Steve Harwell, died at age 56 on Sept. 4.

Also in the '90s, Reubens had a recurring part on the sitcom Murphy Brown, which earned him an Emmy nomination for Outstanding Guest Actor in a Comedy Series. In 2001, the actor starred with Johnny Depp in the crime drama film Blow.

Nine years later, the actor revived his Pee-wee Herman stage show, which opened in Los Angeles and later moved to Broadway. The production was adapted into an HBO special, which was nominated for an Emmy.

In 2016, Reubens reprised his signature role in the Netflix movie Pee-Wee's Big Holiday. Over the next few years, he continued to do mostly TV and voiceover work.

Following the actor's death, a slew of fellow celebs took to social media to pay tribute to the actor.

"No tweet can capture the magic, generosity, artistry, and devout silliness of Paul Reubens," Conan O'Brien tweeted. "Everyone I know received countless nonsensical memes from Paul on their birthday, and I mean EVERYONE. His surreal comedy and unrelenting kindness were a gift to us all. Damn, this hurts."

Look back at Reubens' life and career in pictures below:

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