I, pers. pron., 1st sing
Old English ic, cognate with Gothic, Old Frisian, Old Low German (Frisian, Low German, Dutch) ik, Old High German ih (Middle High German, modern German ich), Old Norse ek, eg (Norwegian eg, Swedish jag, Danish jeg).
From the Old Teutonic *ek, ik, cognate with Old Slavonic azu, Lithuanian az, Latin ego, Greek ego(n), Sanskrit ahám: from Proto-Indo-European *egóm, *ego.
So the evolution of I in English is ego > ek > ik > ich > i > ai. The g devoiced and the ending dropped off, the vowel destressed, the k palatalized to a ch sound, the ch dropped off and the vowel lengthened, and then the vowel diphthongized. Just goes to show how words can become unrecognizable after a couple thousand years.