I've always been interested in hearing peoples thoughts on this, because my assumption is that the answer is different for everyone. Define your view on charisma!

Hmm, that's a tough one. One of the cases where you know exactly what it means, but have a hard time putting it into words.

I'd say it's a certain appealing aura.

The opposite of what Michael is.

he has to be a good speaker. seriously someone who convince you of anything. he doesn't have to be persuasive.

positive, likeable, almost humerous attitude

Well i know what I define as charismatic. But there are a variety of manifestations of that.
Cheeky, Charming, Humble, Vivacious, Dominant. All of those adjectives are charismatic sorts in very different ways.

I think Britney Spears is interesting in relation to this because she historically played and still does to an extent, innocent, coy and pining for a companion, but then theres this glint in her eye which indicates, and has evolved to show in full, a very sexual, domineering side to her where she's clearly in control of the charisma and appeal she has and can manipulate that accordingly. I feel this is what has kept britney relevant to the public, otherwise she'd just be another trashy fallen blonde pop star, but it's her charisma that continues to make her engaging. Shes definitely one just born with it.

For me a charismatic person shouldnt be a reflection of my personality.

This and they need to love Wall-E

I think I will agree that it's a certain je ne sais quoi. It could be... dominance. It could be... street smarts, book smarts, vivaciousness, sweetness, being a funny jerk... etc. or any combination of those. I think varies from person to person.

That's the best definition possible.