No, Mark Calaway (born Mark William Calaway on March 24, 1962 in Houston, Texas), better known as WWE's The Undertaker, is still alive, though he has been a recent victim of Twitter death rumors.
Calaway began his career in 1984 with World Class Championship Wrestling. He moved on to World Championship Wrestling (WCW) in 1989, until 1990 when his contract expired. Calaway then joined the World Wrestling Foundation (later to become Word Wrestling Entertainment in 2002) in 1990; he was the mystery partner of Ted DiBiase at The Survivor Series.
Calaway is married to Michelle McCool, his third wife, and McCool is expecting a baby any day now! He also has two children with his second wife, Sara Calaway, and one child with his first wife, Jodi Lynn.