Ross Martin read a script when it was first given to him, then did a pen-and-ink drawing of the character he was going to play, down to the last detail, glasses, mustache, clothes, posture, shoes, et cetera. Then he brought the sketch to make-up artist Don Schoenfeld, and together they molded his face until it looked like the drawing.
The show was originally titled "The Wild West", but was renamed when it was decided that "The Wild Wild West" sounded better.
Michael Garrison, the creator of the series, died during the second season when he slipped on a spilled drink on his new marble staircase in his new home and fell down the stairs to his death.
Robert Conrad (5'8") wore three-inch heels as Jim West. The CBS casting office had orders not to hire any women over 5'6" for the show.
During the fourth season, Ross Martin had a heart attack and missed several episodes. In production order, Martin did not appear in episodes 93-101, a total of nine. Charles Aidman appeared in four episodes (93-96). William Schallert in two (97-98). Alan Hale Jr. in #99, John Williams in #100, and Steve Carlson in #101. Martin returned in episode #102, "The Night of the Diva", but there were only four more episodes shot after that.