Danny "the Dummy" Matthews had a good gig going. Pretending to be a ventriloquist Matt's puppet, he had a seemingly winning act. However, after each performance, due to his size and appearance people kept mistaking him as a caricature rather than an actual human being. Motivated towards a criminal career due to this, the Dummy battled Batman and Robin of Earth-One. Failing versus them, he focused his attention on the Vigilante and his sidekick Stuff. Years later, Danny killed Stuff leading to Vigilante and Stuff's younger brother who avenged the lad's death and brought Danny the Dummy to justice once more.
Another Dummy on another world was the arch-enemy of the Law's Legionnaire known as the Vigilante and one of the Hand's Five Fingers. This Earth-Two version was more formidable than was Danny, having actually exiled Vigilante and his fellow Seven Soldiers of Victory back in time, although they escaped and cornered the mini-mastermind. Dummy later set up stooges to mimic him with a larger version being the ventriloquist while with a smaller mechanized version of himself.
Known as Skipper, Flipper and Dipper... the trio started a crime wave at high society events until Flipper aka the original Dummy was revealed by his nemesis as the true culprit. Nevertheless, the non-human Dipper at times subbed for his master, such as a member of the Monster Society of Evil where he was revealed as made of wood not flesh and blood like his creator. Nevertheless, this inhuman Dummy had the ability of independent thought like his creator.
It seems that, while Danny and his mechanical "puppeteer" Matt were the inverse dopplegangersof the Dummy duplicates of Skipper and Flipper aka the human Dummy. Dipper aka Earth-Two's wooden Dummy found a counterpart in Earth-One's Brain. The Brain was originally a French scientist who mentally augmented an ape to genius level intelligence and soon after found his own body perish. The ape transplanted his master's mind into a cybernetic harness, and the Brain was born. From this pairing donned the Brotherhood of Evil, of which the Brain was leader.