Question

Who discovered the first exoplanet?

Answer 1

I would say Adriaan van Maanen in 1917.

Explanation:

Know as Van Maanen's Star, it was not recognised as an exoplanet back in 1917 but later spectral analysis and its interpretation in 1990 was the object was possibly an exoplanet.

This paper might interest you:

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1990ApJ...357..216G&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf