Paul Reubens — the comedic actor best known for playing Pee-wee Herman — is dead after a private battle with cancer.

Paul died Sunday night, according to a statement posted Monday on his Instagram account … a statement that revealed, for the first time, the medical crisis with which he’d be dealing — “Paul bravely and privately fought cancer for years with his trademark tenacity and wit.”

We’re told he had a brain tumor 6 years ago, but doctors were able to surgically remove it … and it was considered a successful procedure. It’s unclear what kind of cancer he’d been diagnosed with most recently.

The comedic icon will forever be remembered for his Pee-wee Herman character, which Paul created in 1978 during an improv exercise with The Groundlings. Paul worked with another comedy legend, the late Phil Hartman, to develop the character.

That led to the eventual launch of the “Pee-wee’s Playhouse” TV show in 1986 … and although it was Saturday morning programming, it became a huge hit with kids and adults.

He also brought the character to the big screen with the film, “Pee-wee’s Big Adventure,” which was a huge commercial success.

The movie featured a scene with Pee-wee dancing to the 1958 hit song, “Tequila” by The Champs. The character, and that dance, were so beloved … you can’t hear that song without thinking of Pee-wee.

While Pee-wee is his most iconic role, Paul had been doing live comedy routines long before that. In addition to his time in The Groundlings, he made 14 appearances on “The Gong Show” back in the ’70s.

He’s also done a ton of acting unrelated to Pee-wee — having roles in movies, like “Blow,” “Batman Returns,” “Buffy the Vampire Slayer,” “The Nightmare Before Christmas” and “Doctor Dolittle” … as well as hit TV shows like “Murphy Brown,” “Ally McBeal” and “Everybody Loves Raymond.”

As for his cancer battle — Paul addressed it in a note he’d written, saying … “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.”

Paul was 70 years old.