Back in 1956 he was the male lead in the classic science fiction film Forbidden Planet. If you have not seen this I urge you to do so.
'Early in the 23rd century, the United Planets Cruiser C-57D has been sent to the planet Altair IV, 16 light-years from the Earth. Its mission is to discover the fate of an expedition sent 20 years earlier to establish a colony there. The cruiser is contacted by Dr. Edward Morbius, who radios the crew and warns them to stay away. However, the starship's captain, Commander John J. Adams [Neilsen], decides to land on Altair IV.' [Wikipedia]
The story is sophisticated [based on 'The Tempest'] and the special effects are extraordinary for the time. An excellent 50th Anniversary 2 Disc Special Edition DVD was released in 2006.
I am surprised Forbidden Planet has not been remade. It would be something to see with modern special effects.