Star Trek episode 'Mudd's Women' airs 1966

One of the most popular episode of Star Trek: The Original Series, Mudd's Women, aired October 13, 1966.  It was the first appearance of Roger C. Carmel as Harry Mudd.

The USS Enterprise intercepts Mudd's spaceship and finds out he is transporting three beautiful women to become wives for men on a distant outpost.  However, it appears that Mudd has enhanced the women's beauty by a "Venus drug" of which the effect is only temporary. 

The Enterprise needs dilithium for its power nacelles, but Mudd and his women interfere with Kirk and crew trying to get the crystals.

Star Trek episode "'I, Mudd" airs 1967

Possibly the funniest episode (Episode 8, Season 2) of the Star Trek: The Original Series, I, Mudd aired November 3, 1967.  Although the beginning promises to be drama, the episode soon becomes quite entertaining.  Harcourt (Harry) Fenton Mudd returns on a planet populated only by androids.  They seize command of the Enterprise and take everyone prisoner on the planet.

Capt. Kirk, Spock and the crew devise a way to defeat the army of beautiful female androids but keep a special punishment for Harry Mudd.

Roger C. Carmel is the only actor other than the regulars to play the same character twice during the run of the series.