Titania is the name of the queen of the fairies in William Shakespeare's play A Midsummer Night's Dream. The name was also used as an epithet for some of the daughters of the Titans from Graeco-Roman mythology.
Tatiana, however, is a different name with a different origin. It is the feminine form of the Roman family name Tatianus, which is an adjective that means "of Tatius," where Tatius was the name of a king of the Sabines, who afterwards reigned jointly with Romulus of Rome. I like how such a royal girl had such a royal name.