Old English had a first person pronoun the inflected for four cases and three numbers. I originates from Old English (OE) ic, which had in turn originated from the continuation of Proto-Germanic *ik, and ek; The asterisk denotes an unattested form, but ek was attested in the Elder Futhark inscriptions (in some cases notably showing the variant eka; see also ek erilaz). Linguists assume ik to have developed from the unstressed variant of ek. Variants of ic were used in various English dialects up until the 1600s. The Proto-Germanic root came, in turn, from the Proto Indo-European language (PIE) *eg-.
Old and Middle English first-person pronouns
*Early OE circa 700 CE,:144 late,:117 and ME:120
Old English me and mec are from Proto-Germanic *meke (accusative) and *mes (dative).Mine is from Proto-Germanic *minaz, and my is a reduced form of mine. All of these are from PIE root *me-.
Subject: I'm here; me being here; my being there; I paid for myself to be here.
Object: She saw me; She introduced him to me; I saw myself.
Predicative complement: The only person there was me / I.
Dependent determiner: I met my friend.
Independent determiner: This is mine.
Adjunct: I did it myself.
Modifier: the me generation
The above applies when the pronoun stands alone as the subject or object. In some varieties of English (particularly in formal registers), those rules also apply in coordinative constructions such as "you and I".
"My husband and I wish you a merry Christmas."
"Between you and me..."
In some varieties of non-standard informal English, the accusative is sometimes used when the pronoun is part of a coordinative subject construction, as in
"Phil and me wish you a merry Christmas."
This is stigmatized but common in many non-standard dialects. 
Pronouns rarely take dependents, but it is possible for me to have many of the same kind of dependents as other noun phrases.
^ abcTerminological note: Authorities use different terms for the inflectional (case) forms of the personal pronouns, such as the oblique-case form me, which is used as a direct object, indirect object, or object of a preposition, as well as other uses. For instance, one standard work on English grammar, A Comprehensive Grammar of the English Language, uses the term objective case, while another, The Cambridge Grammar of the English Language, uses the term accusative case. Similarly, some use the term nominative for the form I, while others use the term subjective. Some authorities use the term genitive for forms such as my where others use the term possessive. Some grammars refer to my and mine, respectively, as the dependent genitive and the independent genitive, while others call my a possessive adjective and mine a possessive pronoun.
^Other pronouns may be capitalized when referring to the Deity ("God's in His heaven") and, of course, when beginning a sentence. The capitalization of the first person pronoun is distinctive of English, although it is common in other languages to capitalize a second person pronoun, for example Sie in German.
Howe, Stephen (1996). The personal pronouns in the Germanic languages: a study of personal pronoun morphology and change in the Germanic languages from the first records to the present day. Studia linguistica Germanica. 43. Walter de Gruyter. ISBN3-11-014636-3.