Satella

Satella (サテラ) is the Witch of Envy. She is also simply called "Witch" (魔女 Majo) as who else would be referred to that besides her.

Appearance
Satella is rumored to have silver hair and Elven ears, so it can be assumed that she is an Elf or a Half Elf, all which is very similar to Emilia.

Personality
Contrary to popular belief, Satella and the Witch of Envy are separate personalities, formed when she took in incompatible Witch Genes. The two personalities tend to fight each other.