A number of people have been called Astra. The most prominent one is Astra Logue, a young girl trapped in hell during a botched exorcism by John Constantine. The event scarred him and the Newcastle Crew.
A number of others have appeared. Queen Astra of the child planet Infanta is an ally of Wonder Woman. Another Astra is a member of the Xenobrood, a short lived team after Zero Hour. The Supergirl TV series introduced General Astra, a maternal aunt of Supergirl and a main villain in the first season.
Astra of Infanta was created by Robert Kanigher and Harry G. Peter, first appearing in Wonder Woman #36 (1949). Astra Logue was created by Jamie Delano and John Ridgway, first appearing in Hellblazer #8 (1988).