Conchobar mac Nessa's Clique: Homewreckers
These fellas like to get groovy with their friends' new wives on the honeymoon night. Conchobar may have not gotten down physically with Cúchulainn's wife Emer, since he was afraid of the warrior's wrath, but that hasn't stopped other randy royals from exercising their prerogatives.
Gilgamesh
This Mesopotamian mega-hero has the right, as partially divine king, to sleep with any bride on her wedding night. And, well, he's kind of into it. After Gilgy's subjects started complaining, though, he consulted with the advisers at his lunch table and decided to cut down on his adulterous activities.
Doctor Doom
This Marvel villain doesn't exercise his rights in a good way. Like a true bad dude, he tried to use his powers as ruler to force a Latverian peasant, Gretchen, to sleep with him. Thankfully, another superhero came to help, and the doc has been shunned at the lunch table ever since.
Evenus III
A mythical King of Scotland, Evenus instituted a law in his land, saying that any nobleman had the right to snuggle a virgin on her wedding night. This didn't make him too popular, and he was chased out of his capital by villagers waving axes—all the way to the bottom of the sea. Still, the custom remained intact until King Malcolm III repealed the law years later.