Holly comes from the Old English holegn, the holly tree — the evergreen shrub with shiny dark green leaves and bright red berries, associated with Christmas and winter celebrations across Europe.
Holly entered the U.S. top 1000 in 1939 and was hugely popular in the 1970s-80s, peaking at #19 in 1980. Today it sits in the U.S. top 500. The character Holly Golightly in Truman Capote's Breakfast at Tiffany's (1958) is one of the most iconic literary heroines of the 20th century.
Holly 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 Holly reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.