The adopted son of actress Helen Hayes and playwright Charles MacArthur, MacArthur made his stage debut in The Corn is Green. He won a Theatre World Award for his performance in Arthur Laurents' Invitation to a March on Broadway.
MacArthur gained fame as Danno in the original Hawaii Five-0 series. In addition, he guest-starred on such series as The Love Boat, Fantasy Island, Murder, She Wrote, Bonanza, and Gunsmoke.
Among his other credits are such films as The Swiss Family Robinson, The Battle of the Bulge, The Young Stranger, The Truth About Spring, Cry of Battle, and The Interns.
He is survived by his wife of over 25 years, Helen Beth; four children: Charles P. MacArthur, Mary McClure, Juliette Rappaport, and James D. MacArthur; and seven grandchildren: Ruby Johnstone, Riley Kea MacArthur, Ford and Daisy McClure, Jake, Luke, and Julia Rappaport.
In lieu of flowers, the family requests contributions be made to the Helen Hayes Awards in Washington, D.C.; the Helen Hayes Hospital in Nyack; the Solebury School MOM Fund in New Hope, Penn.; the Palm Desert Community Presbyterian Church, Palm Desert, Calif.; and the Hawaii Theatre in Honolulu.