Agnes is from the Greek hagnē ("pure, chaste"), conflated with the Latin agnus (lamb) — hence the iconography of Saint Agnes always shown with a lamb. Saint Agnes of Rome (c.
Subject of Keats's The Eve of St.
Agnes does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Agnes reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.