One character by this nam
One character by this name is a sea-captain and friend to Viola's brother Sebastian in Twelfth Night.  Another plots with still another character named Sebastian to kill Alonso and is the usurping Duke of Milan and brother of Prospero in The Tempest.  FTP, give this name associated with the most lines of any name in Shakespeare's plays, including those spoken by the friend of Bassanio and title character in The Merchant of Venice.
One character by this name is a sea-captain and friend to Viola's brother Sebastian in Twelfth Night.  
Antonio