Chad Everett, the star of the 1970s TV hit Medical Center, died Tuesday at age 75 after a battle with lung cancer - a diagnosis he allegedly kept secret from his friends, according to actor Kevin Sorbo. Everett was married to actress Shelby Grant, who died in June 2011, for 45 years.

Chad Everett passed away. He was a golfing bud and a good man. I had no idea he had lung cancer. He told none of his friends. Medical Center was one of my favorite shows when I was a kid. RIP........., Sorbo, best known for playing the title character on TV's Hercules: The Legendary Journeys, wrote on his Twitter and Facebook accounts.

Everett starred as Dr. Joe Gannon on Medical Center, a hit TV series from the 1970s. Everett garnered two Golden Globe nominations and an Emmy nod for his portrayal. He also went on to play memorable roles in David Lynch's Mulholland Drive and Airplane II: The Sequel.

Everett had a long-lasting marriage with Shelby Grant, an actress who also appeared on Medical Center. The couple were married for 45 years prior to Grant's death in June 2011.

Everett, a native of South Bend, Ind., had been battling lung cancer for 1 ½ years, his daughter, Katherine Torp, told the AP.

Celebrities took to Twitter to mourn the Medical Center actor.

Really sorry to learn chad everett died today. I loved working with him as old Dean on Supernatural. He was warm, funny, charming. RIP, wrote actor Jim Beaver.

Sad news about chad everett. Super nice guy and will be missed, said Criminal Minds actor Joe Mantegna.

Actress Holly Robinson Peete said she loved Medical Center.

Everett died the same day Hollywood lost legendary television actor Sherman Hemsley.

Comedian Louie Anderson called Everett and Hemsley two really great people.