- Solomon Grundy, born on a Monday, christened on Tuesday, married on Wednesday!
- -- Solomon Grundy src
Solomon Grundy was originally a man named Cyrus Gold, fleeing pursuit a hundred years ago. He died in a swamp during a thunderstorm. A lightning strike, combined with the strange plants in the swamp, reanimated Gold and turned him into a sort of super-zombie. One of the few things he could remember was that he was born on a Monday. Some hobos he encountered and shared this information with dubbed him "Solomon Grundy" after the old rhyme.
At some point, Grundy was captured and imprisoned in Wonder City by Ra's Al Ghul, who wished to understand how his resurrection had been made possible. Grundy was tortured for years, being killed and revived over and over. When Wonder City was shut downn and Ra's and his followers left, Grundy was left behind in the lab. Eventually, the Pinkney Museum was built over the lab and the Penguin found him on his purchase of the property. He left Grundy there, under the Iceberg Lounge, in case he ever needed the muscle. Grundy's prison was contained an antique generator, which would hit Grundy with repeated bolts of electricity to temporarily boost his strength past even his normal Herculean standards.
Although not positively canonical, Solomon Grundy appears in Batman: Arkham City Lockdown in the sewers. This is the exact opposite of what Penguin said, saying how he never lets Grundy out of his cell. It is entirely possible that Penguin does occasionally let Grundy out but this is simply speculation.
Disabling the generator would disorient Solomon, giving a long opportunity to attack him. During Batman's investigation of Arkham City, he faced Grundy, revived by the Penguin, and bested him. Upon his defeat, Grundy's chains--which he had been using as flails--became caught in the machinery of the generator. The gears seized up with the chain tangled in them, trapping Solomon Grundy once again and wrecking the machine, preventing it from shocking him back to life. 
Later, Grundy was reborn on a Monday, waking up at the morgue and breaking out of the cold storage unit his body was held in. 
- Ball and Chain Restraints
- This version of the character is exclusive to the continuity of the Arkhamverse video game series and is an adaptation of Solomon Grundy. The original character was created by Alfred Bester and Paul Reinman and first appeared in All-American Comics #61.
- Solomon Grundy was voiced by Fred Tatasciore.
- Penguin tells Batman that Grundy never leaves his cell, but Grundy is shown in the Gotham sewers in Arkham City Lockdown.
- 7 Appearances of Cyrus Gold (Arkhamverse)
- 2 Images featuring Cyrus Gold (Arkhamverse)
- 1 Quotations by or about Cyrus Gold (Arkhamverse)
- Character Gallery: Cyrus Gold (Arkhamverse)