Gillian is the medieval English feminine of Julian — from the Latin Iuliana ("youthful, of Jupiter"). A top-300 US baby name from 1991 to 2003. Gillian Anderson (born 1968) — *American-British actress; Dana Scully on Fox's The X-Files (1993-2002, 2016-2018) for 11 seasons — the longest-running US science-fiction TV series until Doctor Who surpassed it; Emmy Award (1997) for Outstanding Lead Actress in a Drama Series. Played Margaret Thatcher in Netflix's The Crown season 4 (2020) — winning the Primetime Emmy for Outstanding Supporting Actress in a Drama Series (2021) and the Golden Globe. Sex Education (Netflix 2019-2023) as Jean Milburn. Two Olivier Awards (2000, 2015) and a Tony nomination. Gillian Flynn (born 1971)* — American author of Gone Girl (2012), Sharp Objects (2006), Dark Places (2009); Gone Girl sold 20 million copies. Gillian Jacobs (born 1982) — Community* (2009-2015). Gillian Welch — American Grammy-winning roots musician.
Featured throughout 1990s-2020s American and British culture.
Gillian 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 Gillian reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.