710-779) was the English-born abbess of Heidenheim in Germany — her feast night, Walpurgisnacht (April 30), is the famous German witches' night.
Walpurgisnacht features in Goethe's Faust.
Walpurgis 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 Walpurgis reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.