Niven's three-legged Puppeteers with their brains inside their bodies are definitely not humanoid. Nor are Poul Anderson's less well known Smokesmith the Reardonite or Rax.
One of Anderson's Didonians comprises three temporarily linked bodies. Although each of these bodies is comparable to a Terrestrial animal - rhino, goose and ape - their transient tripartite consciousnesses are entirely alien. See here.
Thus, here are five interesting alien intelligences appearing respectively in four future histories:
Pournelle's CoDominium series;
Niven's Known Space series;
Anderson's Psychotechnic History;
Anderson's Technic History.