[en] This paper reports the discovery and characterization of the transiting hot giant exoplanet Kepler-17b. The planet has an orbital period of 1.486 days, and radial velocity measurements from the Hobby-Eberly Telescope show a Doppler signal of 419.5[SUP]+13.3[/SUP] [SUB]-15.6[/SUB] m s[SUP]-1[/SUP]. From a transit-based estimate of the host star's mean density, combined with an estimate of the stellar effective temperature T [SUB]eff[/SUB] = 5630 ± 100 from high-resolution spectra, we infer a stellar host mass of 1.06 ± 0.07 M [SUB]&sun;[/SUB] and a stellar radius of 1.02 ± 0.03 R [SUB]&sun;[/SUB]. We estimate the planet mass and radius to be M [SUB]P[/SUB] = 2.45 ± 0.11 M [SUB]J[/SUB] and R [SUB]P[/SUB] = 1.31 ± 0.02 R [SUB]J[/SUB]. The host star is active, with dark spots that are frequently occulted by the planet. The continuous monitoring of the star reveals a stellar rotation period of 11.89 days, eight times the planet's orbital period; this period ratio produces stroboscopic effects on the occulted starspots. The temporal pattern of these spot-crossing events shows that the planet's orbit is prograde and the star's obliquity is smaller than 15°. We detected planetary occultations of Kepler-17b with both the Kepler and Spitzer Space Telescopes. We use these observations to constrain the eccentricity, e, and find that it is consistent with a circular orbit (e < 0.011). The brightness temperatures of the planet's infrared bandpasses are T_{3.6\, {\mu m}} = 1880 ± 100 K and T_{4.5\, {\mu m}} = 1770 ± 150 K. We measure the optical geometric albedo A[SUB]g[/SUB] in the Kepler bandpass and find A[SUB]g[/SUB] = 0.10 ± 0.02. The observations are best described by atmospheric models for which most of the incident energy is re-radiated away from the day side.