Mosasaur. I loved seeing one in Jurassic World, even if it was a bit off in size proportions (to what an actual mosasaur would be like.) I fell in love with them after National Geographic did a "Sea Monster" documentary/movie 7ish years ago? It became a game too, and I still have the movie and a copy of the game for the Wii. XD PS this is a Mosasaur:
mine as well. I am a big cat person - so Sabre-toothed tiger too. If you mean dinos? Then: t-rex...I mean who else.
Castoroides, or giant beaver. They were up to 7 feet long, and weighed up to 250 pounds. Funny image shows scale! That would be one scary beaver.
Stegosaurus, Velociraptors, Triceratops, Pterodactyls and Woolly Mammoths. If I had to choose just one, it'd be a close call between the Stegosaurus and Triceratop