MacArthur passed away on Thursday (28Oct10), a family representative tells People.com. Details surrounding the cause of death were not made available as WENN went to press.
The actor seemed destined for a career on the stage and screen, as the adopted son of actress Helen Hayes and her husband, American playwright Charles MacArthur, and he made his big screen debut in 1957 drama The Young Stranger.
MacArthur went on to appear in Walt Disney films Third Man on the Mountain, Kidnapped and Swiss Family Robinson, and in 1961 he made his Broadway debuted opposite a little-known Jane Fonda in Invitation to a March.
The stage performance won him the Theatre World Award for Best New Actor.
He won further acclaim for his roles in 1965 World War II drama, The Battle of the Bulge and Clint Eastwood's 1968 spaghetti Western, Hang 'Em High.
But he is perhaps best known for his role as Detective Dan 'Danno' Williams on the original U.S. TV crime drama Hawaii Five-O, which ran from 1968 to 1980.
MacArthur is survived by his wife of more than 25 years, Helen Beth Duntz, four children and seven grandchildren.
His first two marriages, from 1958 to 1967 to actress Joyce Bulifant, and another, from 1970 to 1975 to actress Melody Patterson, ended in divorce.