.This is so sad. I still dont believe it.

It is believed the 32-year-old killed himself after suffering depression.

A statement issued by the Seven Network said Priestley was a "tremendous young person" who was loved and respected by his fellow All Saints cast members and crew.

"Mark was such a brilliant artist...his work on stage and screen was admired by everybody who knew him," Seven's Director of Programming and Production Tim Worner wrote in the statement.

"His death is such a sad loss. We at Channel Seven will miss his energy and smile.

"Our thoughts and prayers are with Mark's family and friends."

Priestley played male nurse Dan Goldman in Seven's popular hospital series.

In the show's most recent episode, Priestley's character Dan Goldman married his fellow nurse Erica Templeton.

Priestley was born in Perth in 1976, attended private boys' school Aquinas College and graduated from NIDA in 1999 after moving to Sydney.

Fans of the TV show have already expressed their disbelief at the news of Priestley's death.

On Facebook's All Saint's page, fan "Trent" said he was "truly shocked".

"I had seen Mark not all that long ago in Newtown, he looked really happy and he was eating at my favourite pasta bar."

"I just can't believe that I never knew he was suffering depression.

"My thoughts are with his family and cast of All Saints."

My Emblems