Tarmo Oja (born December 21, 1934 in Tallinn, Estonia) is a professor in astronomy at Uppsala University who studies galactic structure and variable stars.
He was the director at the Swedish Kvistaberg Station of the Uppsala Observatory form 1970 until his retirement in 1999.
As a senior professor he continued his observations (work) at the observatory at Kvistaberg until the spring of 2006, when he moved (back) to Uppsala together with his wife Silvi.