Kolker (or Kolk'r) is a supernatural deity, viewed as a supreme being in the religious beliefs of populations in the Alpha and Beta Quadrants, including members of the Brikarian and Yakaban civilizations, occasionally invoked in casual speech. (TNG novel: Survival; NF - Excalibur novel: Restoration)
In 2267, Delacort invoked Kolker's name on a number of occasions. (TOS novel: The Disinherited)
In 2365, Jaan Devin used the phrase "in the name of Kolker" on a number of occasions. (TNG novel: Strike Zone)
In 2366, Paul Estin invoked the epithet "Holy Kolker!" upon seeing Quintin Stone's scars. (TNG novel: A Rock and a Hard Place)
In 2369, James Kelly invoked the epithet "Holy Kolker!" upon seeing Ro Laren in her quarters. (TNG novel: The Romulan Stratagem)
In an alternate timeline 2408, Orion Administrator Mary Mac invoked the epithet "Holy Kolker!" to a suprising dialogue between Commodore Data and the Guardian of Forever. (TNG novel: Imzadi)