  With new data from the Galactic O-Star Spectroscopic Survey, we confirm and
expand the ONn category of late-O, nitrogen-enriched (N), rapidly rotating (n)
giants. In particular, we have discovered two "clones" (HD 102415 and HD
117490) of one of the most rapidly rotating O stars previously known (HD
191423, "Howarth's Star"). We compare the locations of these objects in the
theoretical HR Diagram to those of slowly rotating ON dwarfs and supergiants.
All ON giants known to date are rapid rotators, whereas no ON dwarf or
supergiant is; but all ON stars are small fractions of their respective
spectral-type/luminosity-class/rotational subcategories. The ONn giants,
displaying both substantial processed material and high rotation at an
intermediate evolutionary stage, may provide significant information about the
development of those properties. They may have preserved high initial
rotational velocities or been spun up by TAMS core contraction; but
alternatively and perhaps more likely, they may be products of binary mass
transfer. At least some of them are also runaway stars.
