The name Ludwig was shared by two characters in the Universal Monsters universe.
Father of Maria, Ludwig was woodcutter who lived in Goldstadt. When she was found drowned, Ludwig blamed the Frankenstein monster and, along with Henry Frankenstein and Burgomaster Vogel, led the angry mob that trapped the monster in an old windmill. Even though the mob burned the windmill down, Ludwig refused to rest until he saw the monster's dead body. He ended up falling down into the flooded basement of the mill, where he encountered the still-living monster. The monster then killed Ludwig by drowning him.
(Note that in Bride of Frankenstein, where he is killed, Ludwig's name was changed to Hans. Presumably this was to avoid confusion with the other Ludwig appearing in that film.)
Bride of Frankenstein
This Ludwig was one of Dr. Septimus Pretorius' assistants, alongside Karl. He and Karl helped him rob graves for the parts needed to create the bride of Frankenstein, and then assisted Pretorius and Henry Frankenstein in the actual creation of the bride.