Robert Hobbs was an inventive and obsessive individual. Wanting the best of everything, he used his specialized toys and gadgets to commit thefts seemingly unhindered. That is, until he arrived in Smallville, where he drew the attention of Superboy. The two had a handful of confrontations with one another over the years, from when Hobbs was he costumed criminal known as Humpty Dumpty to his later incarnation as the Curator. Despite his ingenuity, he never best his younger opponent.
Mister Blob was a a retired industrial tycoon who decided to take up the hobby as the Tycoon of Crime, operating several rackets in Metropolis. Unlike his Earth-One counterpart Hobbs, the Tycoon found a grown up Superman opposing him instead. Years later, he assumed the new identity as Mister K, who had bought up all the Kryptonite found throughout Earth-Two to used against his old foe. Finding a criminal named the Flying Tiger trying to infiltrate his mob, the Tycoon realized it was a disguised Man of Steel. What he didn't foresee when setting a trap for Superman was the hero's wife Lois who saved her husband while bringing about the defeat of Blob.