The Wormhole wrote:
According to Memory Alpha
Koloth was meant to be a recurring character.
And I quote you this page:
"Kor was to have appeared in 'Day of the Dove
', but John Colicos was not available."
According to David Gerrold's "Making of..." book, IIRC, Kor was first slated to be the Klingon antagonist returning for "Tribbles". Memory Alpha
is only as reliable as the fans entering the data.
John Colicos had even helped with the creation of the Klingon makeup, as used in "Errand of Mercy", and was quite invested in the character. Fred Phillips forgot that they'd used a greenish brown greasepaint combination, so the "Tribbles" Klingons ended up caucasian.