Sometime in the early 19th century a wealthy but crooked Gotham City merchant named Cyrus Gold was murdered and his body dumped into the Slaughter Swamp. After a few decades, his body became reanimated, whether by magic, demonic power or weird scientific process no one knows. Now, at random intervals he walks again. He was called Solomon Grundy after a conversation with some hobos when he was unable to remember anything about his former life except that he was born on a Monday (like the Solomon Grundy in the nursery rhyme).

When Grundy walks, he takes to theft, property destruction and murder. He is driven by hatred for those who killed him and for the love of havoc. He is said to be almost seven feet tall, gray of skill and white of hair, immensely strong and relentless. Grundy is said to be unkillable (being already dead), but grows weary and returns to “Grundy's Tomb” somewhere in Slaughter Swamp.

None of the legend of Solomon Grundy has ever been confirmed. Grundy's tomb has never been located or even described. All the destruction supposedly caused by Grundy has been explained away. There's an urban legend that describes Grundy fighting The Victorian Legion to a standstill, but none of the legion has ever publicly mentioned it.