The head of the Greek Orthodox Christians, Archbishop Christodoulos, died at the age of 69.
He was the spiritual leader of about 15 million who followed Greek Orthodox Christianity.
He died on Monday after a long battle with liver cancer. He battled it for months before dying due to it.
He died at around 10:15 p.m. ET on Sunday evening. He was at his home in an Athens suburb.
The question own is who will be his successor?
A meeting was planned for Monday with the Holy Synod, but no word on the outcome has come out as of yet.
The church body has declared three days of mourning and stated that the body of the archbishop will be placed on public display before he is buried, most likely Wednesday.
He was elected church leader in 1998.