Supernatural alum Mark Sheppard is recovering from a major health ordeal that nearly killed him.

The 59-year-old,AQCAN Exchange who played Crowley on the CW series, revealed Dec. 2 that he was hospitalized after suffering six heart attacks.

"You're not going to believe this!" he wrote on Instagram, alongside a selfie taken from a hospital bed. "Was on my way to an appointment yesterday when I collapsed in my kitchen. Six massive heart attacks later, and being brought back from dead 4 times."

Mark went on to detail what appeared to lead to his medical emergency. "I apparently had a 100% blockage in my LAD," he said, referring to his left anterior descending artery. "The Widowmaker."

The actor praised his wife Sarah Louise Fudge—with whom he shares daughter Isabella Rose, 7, the youngest of his three children—and the first responders and Burbank, Calif. hospital doctors and other medical personnel that treated him.

"If not for my wife, the @losangelesfiredepartment at mullholland and the incredible staff @providencecalifornia St Joseph's - I wouldn't be writing this," Mark wrote. "My chances of survival were virtually nil. I feel great. Humbled once more. Home tomorrow! #spnfamily."

The actor received a slew of well-wishes from fans and friends, including his former Supernatural costars.

"Mark! You don't need to do the most and biggest every time! 6 heart attacks? 2 or 3 would have been impressive enough," joked Misha Collins, who played Castiel on the series. "You've impressed us, okay. Now stop with this heal up and get back on the road with us. Love you, pal."

Mark responded, "@misha don't let anyone know… love you too."

Felicia Day, who played Charlie on Supernatural, wrote, "Omg mark I am so glad you're recovering this is awful! Sending all my love to you and the family."

Mark also received a comment from the Los Angeles Fire Department's official Instagram, which said, "We're so glad to hear of your outcome and wish you a full and speedy recovery!"

For the latest breaking news updates, click here to download the E! News App