Sea Dog was the second villain introduced in this theme. From the gleeful way that the DM explains that Sea Dog only speaks in Pirate Talk, we can assume that he was revenge for the players' own ridiculous character concepts.
Aqualich is the leader of the Axis of Antagonists, despite not being introduced until the fourth Supers strip. Almost every strip featuring the Aqualich involves at least one fish-related pun.
The Bug is a 1337 hacker and was not introduced until the sixth Supers strip.