Hiss-Men
Only appearing in "Marvel Family" #74. The Hiss-Men are reptiles that resemble humanoid crocodiles even though the Hiss-Men are not related to the Crocodile-Men from the planetoid Punkus. The come from 1,000,000 BC who are battling the humans of that age for control of the world. Needing humans, they create a time-tube to the present day. Dexter Knox uncovers the tube with his metal detector, and with the Marvel's help unearths it. Hiss-Men emerge who fire lava balls at the group, causing the Marvel Family to be summoned, who chase the Hiss-Men back down the tube, but find they have disappeared, so they cap the tube. Dexter keeps watch, but when he falls asleep the Hiss-Men emerge and net him. They then start using their nets to catch more people and bring them down the tube. Billy wakes up and transforms when he hears cries for help, and saves someone. Freddy Freeman hears Profesoor Edgewse being kidnapped, so transforms and defeats the Hiss-Man. One of the Hiss-Men tries to net Mary, telling her 'Come to the past with me!' but she becomes Mary Marvel and defeats her foe. The Marvels fly back to the tunnel, but find Dexter Knox was knocked out, and the tube has been moved so the Marvels do not wreck it. The Hiss-Men they try to capture kill themselves rather than reveal the location. By now over a thousand humans have been kidnapped and a radio alert is given, some Hiss-Men have been killed but there are always more, but the Marvels use a tracker Dexter Knox made to track the time tube, inside a cave. They realize it does not work on the Marvels, so change back to their civilian forms, and go down the Time Tube, but when emerging they are knocked out by the Hiss-Men using a club from behind. They are placed inside a machine and changed into Hiss-Men, and reveal they plan to make an army of Hiss-Men to defeat the humans of their age. The children cannot say their words with their hissing accents, so they try to escape over the walls with their more agile bodies, but are chased back by a dinosaur. They are forced back to the protection of the Hiss-Men, whose walls and weapons keep the monsters out. They pretend to resign themselves to their fate, but throw a note to Dexter through the time tube. He goes through and is told by them what has happened, after which he is able to reverse the machine. The Marvels defeat the Hiss-Men and send the kidnapped humans back to their own time. They then find the battlefield of the humans and Hiss-Men, where the two sides seem deadlocked, and help the humans to win the battle and drive the Hiss-Men into the sea. They use the time-tube to return while in their civilian forms, then become the Marvels and destroy it.
Read more about this topic: List Of Marvel Family Enemies