|Portrayed by:||Daniel O'Herlihy|
|Only Appearance:||Deep Freeze|
|Grant Walker Gallery|
Grant Walker was a famous theme-park mogul.
Walker built his fame and fortune with a series of well-loved theme parks (one of his original "Visioneers" who designed and built his parks was a young Karl Rossum, later an electronics genius and the CEO of Cybertron). All he wanted, it seemed, was to make people happy by entertaining them. Underneath, however, Walker developed a megalomaniacal disorder and became obsessed with the idea of making the whole world as idyllic as one of his amusement parks – by force, if necessary.
As Walker grew older, he feared that he would die before his grand vision was achieved. He became keenly interested in Dr. Victor Fries's work, and the accident that made him the criminal Mr. Freeze. Walker realized that Fries' aging process had been retarded so much as to make him practically immortal. Walker was eager to trade his own humanity for immortality, so he had Freeze broken out of prison and brought to his newest theme park, Oceania, pleading with him to replicate the process on Walker. Freeze was aghast why anyone in their right mind would actually attempt to duplicate that accident, and attempted to talk Walker out of it. Walker's ace in the hole was Nora Fries, whom his agents had saved from death from the explosion at the GothCorp lab in which Freeze had believed she perished. Walker promised he had the means to save her life, and all Freeze had to do was grant his request, which he reluctantly did.
Once the transformation was completed, and Walker was installed in a cryo-suit similar to Freeze's own, Walker wasted no time in preparing his grand scheme: targeting a gigantic, cannon-sized cold gun at Gotham City, planning to freeze it, and ultimately the rest of the world, while a group of his loyal followers inside Oceania would be the only survivors of the human race. With the world frozen, neither Fries nor Walker would require cryo-suits.
However, Batman prevailed on Freeze's better nature, and Freeze helped him and Robin to escape captivity and sabotage Walker's plan, also by playing upon Freeze's pining for Nora. Batman and Robin convinced Freeze that if Nora regained consciousness, there is no way she would love a man who aided and abetted a megalomaniac like Walker. The cannon malfunctioned, and Oceania was destroyed by ice sheets and submerged beneath the ocean.
When Walker regained consciousness, he was alone and trapped in a block of ice that he could not break, even with his cybernetic strength.