Less famous (though still memorable) droids in the Star Wars saga include: 2-1B medic, EV-9D9, Federation battle droid, IG-88, Imperial probe droid, Pit droid, Power droid (Gonk), R5-D4, and Treadwell.
The word "droid" is a contraction of "android", but droids are not necessarily humanoid in appearance.
See also: robots in literature, EditDroid