Katie is the English diminutive of Katherine — from the Greek katharos (pure). Stanford grad in psychology (2021). Katie Holmes (Dawson's Creek), Katie Porter (US Congresswoman).
Subject of countless swimming retrospectives.
Katie 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 Katie reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.