The Robot had two actors provide his voice on Lost in Space — somewhat by mistake
"The Ghost Planet" gives fans a chance to hear the man inside the Robot costume.
Fun fact: The Robot only says "Danger, Will Robinson!" once throughout the entire original Lost in Space series. The immortal line arrives rather late, in the third and final season, in the episode "Deadliest of the Species." Nevertheless, this warning has become the catchphrase of the franchise. The Nineties reboot movie used the URL www.dangerwillrobinson.com in its marketing. The recent reboot has an episode titled "Danger, Will Robinson."
So what made this specific line stick?
Much of the credit should be given to Dick Tufeld, the voice actor who bellowed lines to the Robinson clan. As the voice of the robot, he brought dramatic authority every "Warning!" or "Does not compute!" uttered by the B9 model. He did say those a lot. He also said "Danger!" by itself a good bit.
Tufeld had experience in science-fiction announcing. In addition to his work for the Robot, the Northwestern grad provided the narration to Lost in Space. He also narrated other Irwin Allen shows such as Voyage to the Bottom of the Sea and The Time Tunnel. A decade early, children could hear his deep voice booming out of speakers as the announcer for the radio program Space Patrol. He also served as the announcer for the TV series Zorro, which happened to star future Lost in Space action hero Guy Williams.
Tufeld was the perfect voice for the Robot.
But if you listen closely to Lost in Space, you can hear that Dick Tufeld is not the only voice of the Robot.
Another actor brought that big bucket of bolts to life — Bob May. He was the man inside the suit.
Before stepping inside the boxy costume of B9, May worked as a stuntman, on television Westerns such as Cheyenne and frequently with Jerry Lewis in comedies like The Nutty Professor. Animating the Robot was physical work. But May brought an artful side to the trusty Robinson sidekick, as well.
Check out the Lost in Space episode "The Ghost Planet," for example. In the opening scene, young Will strums an acoustic guitar while the Robot belts out the tune "Santa Lucia," a Neapolitan ballad popularized by crooners Mario Lanza and Elvis Presley. (Oh, and Andy, Barney and Gomer all sing it on The Andy Griffith Show in "The Song Festers," too.)
The melodic singing voice you hear coming from the Robot is Bob May.
That is not the only place you can hear Bob May as the Robot in "The Ghost Planet," though the second instance is more of a goof. Late in the story, as our heroes escape to the Jupiter 2, the Robinsons help an injured Robot to the spaceship. The Robinsons frantically flee the eerie bad guys, shouting over one another. It's a noisy frenzy. Listen closely. You can hear the muffled voice of Bob May shouting his lines from inside the Robot suit.
Normally, Lost in Space would redub the Robot's lines with the voice of Tufeld in post-production. However, in scenes such as this, where many actors are talking over one another, that proved to be impossible.