Paul Reubens 'never forgot a birthday.' Now, his famous friends are sharing stories of his 'heartfelt' videos, cards and texts.

In the many tributes to Paul Reubens — the actor, comedian and producer best known for his character Pee-wee Herman — there's a through line: He had a way of making his friends feel special.

The star — who died Sunday after a private, six-year cancer battle at age 70 — would send personal greetings to close friends and acquaintances on their birthday. They came in the form of videos, cards, memes and pie-in-the-face GIFs. And he had a lot of friends because everyone seemed to be on his recipient list.

Daryl Hannah, who spoke to Yahoo right after news of Reubens's death broke, talked about what a "sensitive, sweet, caring" person her longtime friend was. "Before there was even the internet, he remembered everyone's birthday, sent them messages and the funniest Christmas cards."

So many of the social media tributes posted in the wake of Reubens's death note that thoughtful trait. Jimmy Kimmel said the "brilliant and original comedian," who had over 100 credits including TV's Pee-wee's Playhouse and Pee-wee's Big Adventure,"never forgot a birthday."

In fact, he would "send multiple birthday wishes," Eric Stonestreet shared.

Artist Mark Ryden dubbed him the "ultimate 'birthday king.'" If you were lucky enough to be on his list, you could expect an overflowing flood of texts, gifs and heartfelt messages throughout your special day. He really made you feel loved. He was such a special human being."

Stonestreet and others actually shared the birthday videos, so you can get a glimpse of some of them. "I’m just so thankful I was one of [the people on his list," the Modern Family star wrote. "This is part of one he sent me that I’ll treasure forever. He was a national treasure and a true 1/1."

Kathy Griffin, Ricki Lake, Cheri Oteri and Billy Baldwin also shared videos he sent them.

Like Hannah, actor Norman Reedus was on Reubens's card list — and not just on his birthday. The Walking Dead star wrote that Reubens was the "first person to send me [a] Xmas card, bday card, valentines card [and] new yrs card every single year. Thank u for all the laughs my friend." Kevin Nealon said he "saved all of his holiday cards from over the years. Each one so creative, funny and always personalized with a hand written note."

Conan O'Brien — and everyone he knows — "received countless nonsensical memes from Paul on their birthday, and I mean EVERYONE," he wrote.

Baywatch alum David Hasselhoff, who was roommates with Reubens when they attended California Institute of the Arts, said his "great, great friend" remembered his birthday, with Muppet GIFs, as well as the birthdays of everyone in their class.

Reubens also sent Jane Lynch GIFs of Muppets, including icons Animal and Bert and Ernie.

Beverly D'Angelo recalled Reubens being a gif giver too. "Wanted to share something really fun that Paul did to all his friends on thier birthdays. He would text a short clip of someone getting a pie in the face. EVERY HOUR ALL DAY LONG - this is one of the zillions he sent me."

Patton Oswalt also got pie-in-the-face gifs "ALL DAY" on his birthday. Ditto Wanda Sykes and model/singer Karen Elson.

Griffin was also on the GIF list. She shared one he sent of Jessica Tandy holding a cake in The Birds.

Author Andrew Mayne said he would receive "a dozen in one sitting."

Aaron Paul, who shared a birthday with Reubens, commented on Instagram how it "was really fun exchanging messages with him through the years on our 'special' day."

Padma Lakshmi said she got to know Reubens when he was on Top Chef and "never forgot a birthday" after — "ever!! — and we weren’t that close."

There are just so many celebrities who mentioned famous Reubens's birthday greetings. Joe Manganiello, who worked with him on Pee-wee's Big Holiday and called him his best friend, said, "Paul was subversive, brilliant, witty, and had the biggest heart on the planet… anyone on his Birthday mailing list will know what I mean."

Allison Janney, Jack White, Rosario Dawson and Madonna's manager Guy Oseary and publicist Carrie Byalick, among others, also talked about it.

Garrett Hedlund said "no birthday will be the same" going forward now that Reubens is gone. He made even the quiet birthdays memorable.

On Monday, news broke that Reubens died after quietly battling cancer for six years. Hannah, Griffin and others noted that even they were unaware of his cancer battle.

A final quote from Reubens was included in his death announcement, which said, "Please accept my apology for not going public with what I've been facing the last six years... I have loved you all so much and enjoyed making art for you."