Callista comes from the Greek for "most beautiful (fem.)" (καλλίστη - kalliste). This name is a lesser known name for girls.
Callista mostly means the most beautiful among the women. Center of attention because of its itelligence and beautifulness of body and soul, inside and out. Callista also means a person who is loved and tend to be surrounded by people who adore and admire her.
"She's the most beautiful girl I've ever seen!",
"Yeah, she's a Callista!"