“I am”… I said
To no one there
And no one heard at all
Not even the chair“I am”… I cried
“I am”… said I
And I am lost and I can’t
Even say why
Neil Diamond
“If you please, your Majesty, I’m a bear, I am.”
-the eldest of the Three Bulgy Bears, introducing himself to High King Peter in Prince Caspian
In the mirrors of the many judgments, my hands are the color of blood. I sometimes fancy myself an evil which exists to oppose other evils; and on that great Day of which the prophets speak but in which they do not truly believe, on the day the world is utterly cleansed of evil, then I too will go down into darkness, swallowing curses. Until then, I will not wash my hands nor let them hang useless.
Corwin, in Roger Zelazny’s The Guns of Avalon
Good morning, campers! I’m your Uncle Ernie and I’ll welcome you to Tommy’s Holiday Camp!
It greatly saddens me that we have so little Corwin and so much of the less interesting, whiny, and insecure characters when it comes to the later works in the worlds of Amber, Chaos, and the Shadows. 
From the 2007 Disney animated film, Meet The Robinsons. The protagonist finds out the evil villian was his old roomie from the orphanage. Timestamped at the “reveal” portion [eta - guess I don’t post enough, can’t embed media as a onebox, maybe let me simply drop the link, if anyone’s interested]
Yes! It is I, Mike Yagoobian!
For years after watching the movie, about once a week when one of my kids said, “Dad?”, I’d reply,
Yes! It is I, DAD Yagoobian!
“I am Odysseus, sacker of cities!”
I’m the bad guy?
Indirectly, you just brought to mind:
“Fool! No man can kill me!”
“I AM NO MAN!”
I’m Pod Clock, and I’m here to tell you a thing or two…
At the risk of going on a tangent, this reminds me of Macbeth;
“Despair thy charm,
And let the angel whom thou still hast served
Tell thee Macduff was from his mother’s womb
Untimely ripped.”
I suppose it’s a form of self introduction, though between people who knew each other.
I am not sure if this qualifies as a self-identification but it is definitely iconic:
“KNEEL BEFORE ZOD!!!”
Dissociative self-identification from Felix in Armor:
“It was an odd being which rose from Felix and through him. It was, in fact, a remarkable creature. It was a wartime creature and a surviving creature. A killing creature.
The Engine, Felix thought. It’s not me. It’s my Engine. It will work when I cannot. It will examine and determine and choose and, at last, act. It will do all this while I cower inside.”
― John Steakley, Armor
Now my name is MCA I got a license to kill
I think you know what time it is, it’s time to get ill
[Jeopardy]Things Cecil Adams says {/Jeopardy]
…
Egyptian pharaohs (e.g. in the movie Exodus: Gods and Kings), and Kanye West: “I am a god!”
Variation: Alexander the Great: “I am the son of Amun.”
Well played, but needs to be in the form of a question. 
“I…I…I…I am still Emp…e…ror!” - the dying Skeksis Emperor in Dark Crystal.
I am the only daddy you got. I am the damn paterfamilias!
[Steve Rogers, explaining things with a bloodied mouth]
I can do this all day.
[/Steve Rogers, explaining things with a bloodied mouth]
I am what I am.