Help me build the Big Five Thousand.

For context, I've decided to make a list of fauna species (preferably megafauna) called The Big Five Thousand loosely inspired by The Big Five, which is an accepted list of African fauna species who are considered risky and dangerous to trophy hunt. I myself don't condone this at all, but for the sake of quantifying the average physical strength and resilience, and also imagining how dangerous and risky hunters would consider killing these species, I've decided to extend the list taking to account the countless extinct animal species there are.

If you have any suggestions, list an animal species you think are plausibly, or want to see depicted as, dangerous. They can be predatory, territorial, and intelligent (animals are sentient, sensitive, and intelligent in their own right, more than we credit them for). If you would like to see an interesting dinosaur or other prehistoric animal species on this list, do mention how you think they would behave including their general temperament, cognative abilities, social structures, and semblance of primitive vocal calls and language, as well as levels of perception and self awareness (how they make sense of and interact with their surroundings), and how greatly they value their own self preservation and other members of their species. All of these personality and behavioral aspects play into their intelligence. In addition, you can take inspiration from real world studies or make speculative, plausible, and hypothetical guesses for how they would use their anatomy in a combat situation whether it be their natural strength and size, agility and speed, or hide/armor. If I end up writing or adapting your ideas I will credit you for them. Making up a hypothetical, analytical list of five thousand dangerous animals is easier and fun as a collaborative thought experiment.