Willy was one of three warbot caretakers of Talwyn Apogee.  He, Cronk, and Zephyr always argued over who was superior.  Willy was small, excitable and apparently waved his arms around a lot.  Unfortunately, he never survived the trio's last battle before the events of Ratchet & Clank Future: Tools of Destruction. 
Willy was not referenced in any game in the Ratchet & Clank series, but was mentioned by design director of Insomniac Games Brian Allegeier in an interview with Official PlayStation Magazine.