This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Simurgh (Persian)
The simurgh is a benevolent bird in Persian mythology and literature. It is sometimes equated with other mythological birds such as the phoenix and the huma, though it must be understood as a completely different mythological creature of its own.
The Simurgh is depicted in Iranian art as a winged creature in the shape of a bird, gigantic enough to carry off an elephant or a whale. It appears as a peacock with the head of a dog and the claws of a lion, also with a human face. The Simurgh is inherently benevolent and unambiguously female. Being part mammal, she suckles her young.