Galaxy Quest - By Grabthar's Hammer
"By Grabthar's Hammer, by the suns of Warvan, you shall be avenged."
An oath uttered on someone or something on occasion of grave importance. It was first used in the film Galaxy Quest .
As with both Grabthar's Hammer and the Suns of Warvan, the oath is noteworthy for being fictional within an already-fictional universe. As such, it has no direct analog in American English.