A series of historical studies examines the roles and influence of queens in Spain, arguing that social traditions often constrained women yet individual consorts or regnant queens frequently shaped political outcomes through circumstance, personality, and weak or absent male counterparts. The work combines biographical sketches with archival research and commentary on courtly customs, succession issues, and the contrast between ceremonial status and practical authority, tracing how specific women at the throne affected governance and national affairs across several centuries.