I'm seeing a few tweets like this today: "BOTD, Jonathan Harris."
Doctor Zachary Smith was a stowaway on Lost in Space's Jupiter 2 spaceship when it lifted off from Earth on its journey to a planet orbiting Alpha Centauri. The character, as played by Jonathan Harris, started off as a somewhat mysterious "foreign agent" who was an onboard threat to the Space Family Robinson -- his efforts knocked the flying saucer off its flight path; hence, "lost in space". However, as episodes passed throughout the first season of that truly horrible television series, Dr. Smith became a bumbling, selfish, and sneaky fool -- which is how he is remembered today by those who grew up with the show, or watched it in its original run on the NBC network (1965 to 1968).
Lost in Space was a treat-bag of absurdities. It was made at the same time as Star Trek, but looked at least a decade older, due mainly to its poor design work....which helped render the series as 'old' right out of the gate.
But there was some appeal in the form of the interplay between the "Robot", Dr. Smith, and young Will Robinson (played by Bill Mumy).
Dr. Smith, to the Robot: "You watch your mouth, you bellicose bumpkin." (Like that.)
Despite a lengthy filmography, Jonathan Harris (1914 - 2002) will forever be remembered for giving life and comedic dimension to Doctor Zachary Smith.
"Have no fear, Smith is here!"