Ignatius is the pet iguana of Superman's archenemy Lex Luthor. Thus far, he has only appeared in the cartoon series Krypto, the Superdog and is one of Krypto's main enemies in the series.

Like Luthor, Ignatius is very intelligent, vain, and is morally ambivalent about making others suffer for personal gain; however, he is effete, selfish, and tends to behave in a much less dignified manner than Luthor. He is also more prone to engaging in frivolous (and dangerous) personal whims, such as employing a growth ray to enlarge a bug for his supper, or using a wind tunnel to harvest one of Krypto's hairs as part of a scheme to grow himself a lovely fur coat. Ignatius is voiced by Scott McNeil.