It is claimed that as a twelve-year-old Dirichlet spent his pocket money on mathematics books. He graduated from U Cologne aged sixteen and went to Paris to act as a tutor. While there he taught Poisson and published a paper on Fermat's last theorem which brought him fame. Returning to Germany, he joined the faculty at U Cologne before moving to U Berlin in 1828. In 1855 he succeeded Gauss as Professor at U Göttingen and, in the same year, he was elected FRS. He married a sister of the composer Mendelssohn and has a lunar crater named after him.

http://scienceworld.wolfram.com/biography/Dirichlet.html Portrait.