Count of Trastámara

The Count of Trastámara (Condado de Trastámara ) is a noble title granted by Juan II of Castile to Pedro Álvarez Osorio on the 4 February 1445 in San Martín de Valdeiglesias. Its name comes from the Latin Tras Tamaris, referring to the Tambre, a river which runs through Galicia. The title of Earl of Trastámara had previously been granted for life to others, including Alvar Núñez Osorio and future Enrique II of Castile, founder of the House of Trastámara.

Counts of Trastámara

• Pedro Álvarez Osorio, I Count of Trastámara;
• Álvaro Pérez Osorio, II Count of Trastámara (I marqués de Astorga);
• Pedro Álvarez Osorio, III Count of Trastámara;
• Álvaro Pérez Osorio, IV Count of Trastámara;
• Pedro Álvarez Osorio, V Count of Trastámara;
• Álvar Pérez Osorio, VI Count of Trastámara;
• Antonio Pedro Álvarez Osorio, VII Count of Trastámara;
• Alfonso Pérez Osorio Velasco y Herrera, VIII Count of Trastámara;
• Pedro Álvarez Osorio, IX Count of Trastámara;
• Álvar Pérez Osorio, X Count of Trastámara;
• Antonio Pedro Sancho Dávila y Osorio, XI Count of Trastámara;
• Ana Dávila y Osorio, XII Countessa of Trastámara;
• Melchor de Guzmán y Osorio, XIII Count of Trastámara;
• Ana de Guzmán Osorio y Dávila, XIV Countessa of Trastámara;
• Ventura Osorio de Moscoso y Guzmán Dávila y Aragón, XV Count of Trastámara;