Hmmm...
CJ Cherryh's come up with some very solid aliens in her books, both humanoid and non-humanoid. Her Faded Sun trilogy gave us the Mri and Regul (both humanoid), and her Chanur series the Knnn, T'ca and Chi (non-humanoid methane-breathers), Mahendo'sat, Hani, Stsho, and Kif (humanoid). These are the series I'm most familiar with, though she is a prolific writer--lots of material to draw from.
