Old English yfel (Kentish evel) "bad, vicious, ill, wicked," from Proto-Germanic *ubilaz (cf. Old Saxon ubil, Old Frisian and Middle Dutch evel, Dutch euvel, Old High German ubil, German übel, Gothic ubils), from PIE *upelo-, from root *wap- (cf. Hittite huwapp- "evil").
"In OE., as in all the other early Teut. langs., exc. Scandinavian, this word is the most comprehensive adjectival expression of disapproval, dislike or disparagement" [OED]. Evil was the word the Anglo-Saxons used where we would use bad, cruel, unskillful, defective (adj.), or harm, crime, misfortune, disease (n.). The meaning "extreme moral wickedness" was in Old English, but did not become the main sense until 18c. Related: Evilly. Evil eye (Latin oculus malus) was Old English eage yfel. Evilchild is attested as an English surname from 13c.