"By Grabthar's Hammer, by the suns of Warvan, you shall be avenged." Edit
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 Sons of Warvan, the oath is noteworthy for being fictional within an already-fictional universe. As such, it has no direct analog in American English.