A handwritten letter from a Pittsburgh children’s oncology ward is ripping hearts out across the internet this weekend — and it reveals the jaw-dropping secret life of Steelers offensive tackle Dan Moore Jr., the 6-foot-6, 315-pound “gentle giant” fans have nicknamed “Keanu Reeves” because of his uncanny resemblance to the John Wick star.

The anonymous letter, posted Thursday by a UPMC Children’s Hospital nurse who says she finally had to “tell the world,” details how Moore has quietly donated blood and platelets nearly 100 times over the past five years — an almost unheard-of frequency made possible because he carries an extremely rare blood subtype that is “like liquid gold” for pediatric leukemia patients.

“Most people with his blood type donate once or twice a year at most,” the letter reads. “This man shows up every 14–21 days like clockwork, no cameras, no announcements, just a hoodie and a smile. Because of him, children who had weeks to live are now in remission and blowing out birthday candles.”

Moore, 27, possesses the ultra-rare Bombay phenotype (hh blood group), a genetic trait found in roughly 1 in 10,000 people in India and even fewer worldwide. It allows him to donate to virtually any patient without triggering deadly reactions — a lifesaver for kids whose bodies reject standard transfusions during aggressive chemo.

Hospital records leaked alongside the letter (with patient details redacted) show Moore began donating in 2020 after a rookie visit to the oncology floor left him in tears. A 7-year-old boy named Mason, battling acute lymphoblastic leukemia, needed emergency platelets that night. Standard donors were incompatible. Moore rolled up his sleeve on the spot — and Mason survived.

From that night on, sources say Moore restructured his entire off-season around donation windows. He flies back to Pittsburgh on off-days during away games. He schedules sessions at 6 a.m. before practice so coaches never notice the bandage under his sleeve.

“He’ll finish a game on Sunday, hop a red-eye, donate Monday morning, and be back at practice Tuesday like nothing happened,” one teammate told The Post. “We just thought he was super religious about recovery shakes.”

The “Keanu Reeves” nickname started in 2022 when Moore grew out his hair and beard for charity (he later cut it and donated the ponytail to kids with hair loss). Fans at training camp started yelling “Whoa!” every time he walked by. He leans into it — signing autographs “Neo” and once showing up to a blood drive in a full black Matrix trench coat.

But Moore has never sought credit.

When UPMC tried to honor him publicly last year, he reportedly begged them not to: “Those kids are the brave ones. I’m just a big dude with weird blood.”

That all changed Thursday when the nurse’s letter exploded on TikTok (42 million views and counting). The note ends with a gut-punch:

“To the man everyone calls Keanu: We finally learned your real name is Dan. Thank you for giving our babies tomorrow. You don’t need a cape. You already have a black and gold jersey.”

Steelers Nation lost it.

Coach Mike Tomlin, visibly choked up at Friday’s press conference, said: “That’s the type of human being we have in that locker room. Proud doesn’t even cover it.”

Quarterback Russell Wilson posted a photo hugging Moore with the caption: “Real heroes wear 65.”

Even Keanu Reeves himself chimed in on Instagram: “Dan Moore Jr. — you’re the real John Wick. Honored to share a face with a legend.”

Moore, notoriously media-shy, finally broke his silence Saturday outside the team facility. Bandage fresh on his left arm from that morning’s donation, he told reporters:

“I’m just a guy from Beaumont, Texas, who got lucky enough to play a kids’ game for a living. If my blood can buy one more Christmas morning for a child, I’ll keep showing up until they tell me I can’t.”

He then got in his truck — which has a faded “Be The Match” sticker on the back window — and drove away.

UPMC says demand for Bombay-phenotype donors has spiked 800% since the letter went viral. The hospital is now calling it “The Dan Moore Effect.”

As one recovering teen patient wrote on X: “He gave me 97 tomorrows. I’m gonna make every single one count.”

In a league full of loud heroes, Pittsburgh just found its quietest — and maybe its greatest.

Here we go, Dan. Here we go.