sonneteer n : a poet who writes sonnets
Sonneteer is an archaic term for a poet who composes sonnets, though the individual may not necessarily write poetry exclusively in that particular poetic form. It is also used as a term of derision for a poet who is perceived as being minor or insignificant. Contemporary poets who compose sonnets often choose to refer to themselves simply as sonnet writers.
These links are to sites with texts in English only: