O.E. hræfn (Mercian), hrefn; hræfn (Northumbrian, W.Saxon), from P.Gmc. *khrabanas (cf. O.N. hrafn, Dan. ravn, Du. raaf, O.H.G. hraban, Ger. Rabe "raven," O.E. hroc "rook"), from PIE base *qer-, *qor-, imitative of harsh sounds (cf. L. crepare "to creak, clatter," cornix "crow," corvus "raven;" Gk. korax "raven," korone "crow;" O.C.S. kruku "raven;" Lith. krauklys "crow").
"The common raven is easily tamed, but is mischievous and thievish, and has been popularly regarded as a bird of evil omen and mysterious character." [OED]
O.E. also used hræmn, hremm. The raven standard was the flag of the Danish Vikings.