Jalāl ad-Dīn Muhammad Balkhī Rumi (1207 - 1273) was a thirteenth-century poet, theologian, and Sufi mystic from Iran. Most of his works were written in Persian, but he also wrote in Turkish, Arabic, and Greek.
His full name is Jalāl ad-Dīn Muhammad Balkhī, and Rumi is just kind of a popular nickname, literally meaning "Roman" and given to him because he spent so much time in the Eastern Roman Empire.
He is also known as Mawlana in Iran (various spellings of this word exist, depending on the way people in different countries pronounce it: Mowlana or Maulana or Mawlana or Mevlana), which is a term of Arabic origin meaning "our master."
Until his late thirties, Rumi was a traditional religious teacher. Then he met a wandering dervish by the name of Shams Tabrizi, who became his friend and mentor... and changed the course of his life. Rumi mentions Shams Tabrizi in his poems and describes his initial encounter with this dervish: "What I thought of before as God, I met today in a human being."
Rumi is best known for his epic poem Masnavi.