"Sionis Industries, better steel today and tomorrow."
-The Sionis Industries slogan
Sionis Industries is a company owned by Roman Sionis that manufactures steel.
When Black Mask learned that Wayne Enterprises and Daggett Industries were competing against Sionis Industries for a government contract to build a new space station Sionis hired Clayface to sabotage his competition. To protect his identity Sionis even had Clayface pretend to sabotage Sionis Industries. In the end the U.S. government gave the contract to Roman Sionis and Sionis Industries built the space station.