Thea comes from the Greek thea (θεά), meaning "goddess" — the feminine of theos (god). It is also the short form of Dorothea (gift of God) and Theodora (gift of God). In Greek mythology, Theia was a Titan, mother of the sun and moon.
Thea has been rising rapidly in the U.S., entering the top 1000 in 2009 and climbing into the top 250.
Thea 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 Thea reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.