  The spectrum of singly-ionized iron (Fe II) has been recorded using
high-resolution Fourier transform and grating spectroscopy over the wavelength
range 900 {\AA} to 5.5 {\mu}m. The spectra were observed in high-current
continuous and pulsed hollow cathode discharges using Fourier transform (FT)
spectrometers at the Kitt Peak National Observatory, Tucson, AZ and Imperial
College, London and with the 10.7 m Normal Incidence Spectrograph at the
National Institute of Standards and Technology. Roughly 12 900 lines were
classified using 1027 energy levels of Fe II that were optimized to measured
wavenumbers. The wavenumber uncertainties of lines in the FT spectra range from
10-4 cm-1 for strong lines around 4 {\mu}m to 0.05 cm-1 for weaker lines around
1500 {\AA}. The wavelength uncertainty of lines in the grating spectra is 0.005
{\AA}. The ionization energy of (130 655.4+-0.4) cm-1 was estimated from the
3d6(5D)5g and 3d6(5D)6h levels.
