This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Lavellan (Scottish)
In Scottish folklore, a Lavellan, làbh-allan, la-mhalan or la-bhallan is a creature from northern Scotland. It was generally considered to be a kind of rodent, and the name "làbh-allan" is also used for a water shrew or water vole in Scottish Gaelic. It was however, reportedly larger than a rat, very noxious, and lived in deep pools in rivers.
Its poisonous abilities were legendary, and it was said to be able to injure cattle over a hundred feet away. A lavellan’s appearance is unclear and unassuming; at the very least, it is believed to be small and furry. Sibbald believed it had the head and color of a marten, while other accounts describe it as resembling a shrew or a lizard. It has bright eyes and moves very quickly.