ego

"I", but you will meet the other cases far more often than this one. The forms are ego (subject), me (object and ablative), mihi (to or for me) and mei (of me), and Latin normally leaves the nominative out altogether, because the verb ending already says who is speaking: "venio" is a complete sentence meaning "I come".

That makes the appearance of "ego" meaningful. When a writer does put it in, it is for EMPHASIS or contrast, so "ego hoc feci" is closer to "I am the one who did this" than to a flat "I did this".

Note "mecum" for "with me": the preposition "cum" attaches to the back of the pronoun rather than standing in front of it, and the same happens with "tecum", "nobiscum" and "secum". The plural of "ego" is not a plural form of the same stem but a separate word, "nos".