Hattie is the diminutive of Harriet — itself the feminine of Harry, ultimately from the Germanic Heimrich, meaning "home ruler." The name was hugely popular in the 19th century as the everyday form of Harriet.
Hattie has returned strongly in the 2010s and 2020s as part of the vintage revival. The actress Hattie McDaniel was the first Black actor to win an Academy Award (for Gone with the Wind, 1939). Today the name sits in the U.S. top 500.
Hattie 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.
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In Pythagorean numerology the letters of Hattie reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.