When he decided not to continue studying, his mother, who later became an executive of a foreign film company, was disappointed because it was expected that he would follow in his father's footsteps as an insurance broker.

After working as a welder, cost accountant and aircraft-parts inspector during World War II, Williams became a salesman in the luggage department at Wanamaker's.

He quickly found great success with assignments resulting in photographs in newspapers and magazines, including Harper's Bazaar as well as on billboards and book covers.

He then adopted the name Guy Williams in the 1940s on the advice of his agent Henry Willson after a director refused to cast him because of his on-screen moniker, Guido Armando, that sounded "too foreign".

In 1948, to advertise cigarettes while skiing, Williams did an extensive filming trip accompanied by Janice Cooper, a John Robert Powers model.

Guy Williams appeared in small supporting roles in films, including: In 1953, he suffered a serious accident when he fell from a horse and was dragged over 200 yards, resulting in a long scar on his left shoulder.

Early in 1957, Williams appeared twice in the role of Steve Clay in the television series Men of Annapolis, a military drama set at the United States Naval Academy.

His character had been created as a replacement for Adam Cartwright, since actor Pernell Roberts planned to leave the show at the end of that season, thus allowing the format with four regular leads to continue.

Guy Williams played Professor John Robinson, an expert in astrophysics and geology, who commanded the mission of the Jupiter 2 spaceship, taking his family in a voyage to colonize the Alpha Centauri star system.

After Lost in Space, Guy Williams decided to retire in order to better enjoy his wealth which had been generated by investments in several businesses, buying and selling on the stock market.

In subsequent years, Williams also brought to Argentina some of the original cast members of the Zorro series, including Henry Calvin who performed as Sergeant Garcia.

Williams even formed a circus (Circo Real Madrid) with the local fencing champion, and later actor, Fernando Lupiz, traveling all over South America (1977).

This includes the Zorro Television Companion, detailing the making of the Disney series,[20] as well as a biography by Antoinette Girgenti Lane, Guy Williams: The Man Behind the Mask (2005).

[21] A collection of original Zorro short stories, some inspired specifically by Guy Williams, was edited by Richard Dean Starr and released in 2008.