I'm a fan of Kelpies and Dragons and Sphnixes. I also really like Manticores, Centaurs, Chimeras and pretty much any of those dangerous monsters that are found in legends or in... Harry Potter. xD Though HP did kinda steal them. Also, any monsters with a really interesting story to them, like Minotaur.

Kelpies, for those who don't know them:

"The kelpie is a supernatural shape-shifting water horse from Gaelic folklore that is believed to haunt the rivers and lochs of Scotland. In Orkney a similar creature was called the Nuggle, and in Shetland a similar creature was called the Shoopiltee. It also appears in Scandinavian folklore where it is known by the name Bäckahästen, the brook horse.

In Scandinavia, the brook horse was a transformation of the Nix, a water spirit in the shape of a man. It was often described as a majestic white horse that would appear near rivers, particularly during foggy weather. Anyone who climbed onto its back would not be able to get off again. The horse would then jump into the river, drowning the rider. The brook horse could also be harnessed and made to plough, either because it was trying to trick a person or because the person had tricked the horse into it."