There is Mimir, the Jotun (and Odin's uncle) of Memory. The Nornir, the three maidens that weave together Wyrd, or "fate." There are Odin's ravens, Muginn and Huggin, Memory and Thought. There is Odin himself of course. Forseti was said to be one of the wisest of the gods. There is Kvasir who is also one of the wisest. A few other Giants that Odin matched his wits against (and won).
In Greek Mythology, Athena was the goddess of wisdom, familiarly seen with an owl. (In Roman Mythology she was Minerva).