Just when you thought your brother and sisters were bad; meet six of the baddest mother-fuckers in history. Oh and they all have the same mother and father. You've alread met Cerebus now meet his brothers and sisters.
Nemean Lion:The first labor for the hero Hercales, was to rid the Nemean plain of the wild, enormous and extremely ferocious beast known as the Nemean Lion.
Ladon: This bad boy has one hundred-heads and it's a dragon. He guards the garden of the Hesperides and in it the tree with the golden apples.
Chimera: Chimera is a monster, depicted as an animal with the head of a lion, the body of a she-goat, and the tail of a dragon (sometimes it has multiple heads). It terrorized Lycia , but was eventually killed by the Corinthian hero Bellerophon.
Sphinx:
The Greek Sphinx was a demon of death and destruction and bad luck. It was a female creature, sometimes depicted as a winged lion with a feminine head, and sometimes as a female with the breast, paws and claws of a lion, a snake tail and bird wings. She sat on a high rock near Thebes and posed a riddle to all who passed. 
Hydra- The Hydra which lived in the swamps near to the ancient city of Lerna in Argolis, was a terrifying monster The Hydra had the body of a serpent and many heads up to 500 of which one could never be harmed by any weapon, and if any of the other heads were severed another would grow in its place. Also the stench from the Hydra's breath was enough to kill man or beast. 