Far-ultraviolet spectra of AGNs and stars observed by the Far-Ultraviolet Spectroscopic Exporer (FUSE) satellite are analyzed to obtain measures of O VI 1031.93 Å absorption occurring over very long paths through Milky Way halo gas. Strong O VI absorption is detected along most extragalactic sight lines observed by FUSE. The observations reveal the existence of a widespread but irregular distribution of O VI in the Milky Way halo as envisioned by Lyman Spitzer in his pioneering 1956 theoretical paper predicting the existence of a hot gaseous galactic corona. The FUSE observations imply an O VI exponential scale height of 2.7±0.4 kpc. The ratio of C IV to O VI ranges from ~0.15 in the disk to ~0.6 along extragalactic sight lines. The changing ionization state of the gas from the disk to the halo is consistent with a systematic decrease in the scale heights of Si IV, C IV, N V, to O VI from ~5.1 to ~2.7 kpc. While conductive heating models can account for the highly ionized atoms near the disk, a combination of models (and processes) appears to be required to explain the highly ionized atoms found in the halo. The greater scale heights of Si IV and C IV compared to O VI suggests that some of the Si IV and C IV in the halo may be produced in turbulent mixing layers or by photoionization by hot halo stars or the extragalactic background.