His wife issued a statement to Deadline confirming his death after a private battle with the disease.
“With an open heart, I wish to share with the world that my beloved husband, Julian McMahon, died peacefully this week after a valiant effort to overcome cancer,” Kelly McMahon said.
Tributes to the actor have started pouring in, with fans and peers reminiscing on their favourite characters played by the McMahon.
“I can hardly believe he is gone, this is just terrible news to wake up to,” Nine’s entertainment reporter Richard Wilkins told Today.
“He was a nice fella, we used to cross paths a bit doing the G’day USA things, but he was very much based in LA.”
“Julian will be very fondly remembered by all who came in his path. He was a nice guy… he epitomised tall, dark and handsome.
“He’ll be very sadly missed today. I can’t believe he’s gone.”
His cancer diagnosis and battle with the disease were not public knowledge.
McMahon was born in Sydney on July 27, 1968. His father was Billy McMahon, who served as Prime Minister of Australia from 1971 to 1972.
He is best known for his starring role as Dr. Doom in two Fantastic Four Movies as well as his several beloved soap opera characters throughout his career.
He got his start in the industry as a model before transitioning to a lead role in the short-lived Aussie daytime soap opera The Power, The Passion.
McMahon also appeared in the beloved Home and Away before making his feature acting debut as a lead in the 1992 Australian-American film Wet and Wild Summer!
Fans of the show took to X to pay their respects.
“Thank you Julian McMahon for bringing Cole Turner to life. Thank you for my favourite childhood memories of watching Charmed,” one X user wrote (formerly Twitter).
“I watched a lot of CHARMED when I grew up so I first saw Julian McMahon as Balthazar. What a fun actor. 56 is too young. Rest In Peace,” SNL writer Will Landman said.
“This one hurts loved Julian in so many things. RIP,” another fan wrote.
McMahon won a Golden Globe nomination for playing the handsome and charming Dr Christian Troy on FX’s hit plastic surgery drama Nip/Tuck, which ran for six seasons.
The Australian actor was once married to singer and actor Dannii Minogue. The pair were married from 1994 to 1995 after meeting on the set of Home and Away.
He also had a daughter with his second wife, Baywatch star Brooke Burns, in June 2000, before the pair divorced in 2001.
He married Kelly Paniagua (now Kelly McMahon) in 2014.