If you check out his credits, it really isn't a surprise. His career started with another "G," Godzilla. Takei, whom has done voice work for shows like transformers, scooby doo, the super hero squad tv show, etc, actually did voice work on a Godzilla movie in 1955. He has since lent himself to other science fiction shows such as Twilight Zone, Heroes, and an obscure tv show called Star Trek.
You need another G. The voice he does on Super Hero Squad is Galactus. So we have George Takei, Giant Poster, Godzilla, and Galactus.