Gwen is from the Welsh gwen ("white, fair, blessed, holy") — the feminine of gwyn and the root of Gwendolen, Gwyneth, and Guinevere. Gwen Stefani (born 1969) — American singer-songwriter; lead vocalist of No Doubt (whose Don't Speak topped charts in 17 countries) and solo artist whose Hollaback Girl (2005) was the first US single to sell one million digital downloads. Co-founder of L.A.M.B.
Gwen 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 Gwen reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.