  We present a companion of the \le 2 Myr young classical T Tauri star GQ Lup
in the Lupus star forming region at 140 \pm 50 pc from imaging, astrometry, and
spectroscopy. With direct K-band imaging using VLT/NACO, we detected an object
6 mag fainter than GQ Lup located 0.7 arc sec west of it. Compared to images
obtained 2 to 5 years earlier with Subaru/CIAO and HST/PC, this object shares
the proper motion of GQ Lup by 5 and 7 sigma, respectively, hence it is a
co-moving companion. Its K-L' color is consistent with a spectral type early to
mid L. Our NACO K-band spectrum yields spectral type M9-L4 with H2O and CO
absorption, consistent with the new GAIA-Dusty template spectrum for log g = 2
to 3 and Teff = 2000 K with ~2 Rjup radius at ~140 pc, hence few Jupiter
masses. Using the theoretical models from Wuchterl & Tscharnuter (2003),
Burrows et al. (1997), and Baraffe et al. (2002), the mass lies between 1 and
42 Jupiter masses.
