Pedro Garavito y Vilela de Sanabria was born to a noble family at Alcántara, studied at the University of Salamanca, and entered the Observant Franciscans at sixteen in 1515. He held every office of the Spanish Franciscan province by his late thirties and refused the ones offered after; he became increasingly convinced that the Observant Franciscan reform had itself relaxed too far from primitive Franciscan poverty.
From 1538 he led a new and stricter reform within the Franciscan family — the Discalced Franciscans, popularly the Alcantarines after him. The Alcantarine houses were tiny (no more than eight friars), built of mud and unpolished timber, with cells of seven feet square (Peter himself slept sitting up for forty years to avoid even the relative comfort of lying down). The friars wore patched habits, went barefoot through the Castilian winter, and observed perpetual abstinence from meat, fish, wine, and eggs.
He was the spiritual director of the young Teresa of Ávila from 1559 until his death. She records in her Life that her confessors had been confounded by her mystical experiences until he came; he immediately confirmed her supernatural reality, encouraged the Carmelite reform she was contemplating, and represented to her — by his sheer practical asceticism — the way of poverty her own reform should embrace. He died at the Alcantarine convent of Arenas de San Pedro on October 18, 1562, soon after Teresa had founded the first Discalced Carmelite convent at Ávila. Canonized 1669.