Mattiaca is a goddess known from a singl inscription found at East Wiesbaden in Germany (which in Roman times was known as Aquae Mattiacae) where she is invoked as Dianae Mat[ti]acae. The Roman name for the site indicates that Mattiaca was probably considered a triple goddess and a tutelary deity both of the sacred waters associated with her cult and the tribe of the region, the Mattiacii. Her name is also preserved in the ancient name for Marburg, Germany (Mattium) and Wiesbaden (Mattiacum). Her name is derived from the reconstructed proto-Celtic element *matu- (bear) and possibly *āku- (fast) or ak^wā- (water) thus she is the 'Bear of the (fast-flowing) Waters'. Some have proposed that she is cognate with the deity Artio. However, from her statue it would seem that Artio was a harvest and fertility daity whilst Marriaca seems to be a water deity; thus the association is made in terms of the names only.