Tarhiel
Tarhiel is a Wood Elf enchanter who falls from the sky in the Bitter Coast near Seyda Neen after an experiment goes horribly wrong.
He is the proud creator of the Scrolls of Icarian Flight, which fortify Acrobatics by 1000 pts for 7 seconds. In his eagerness to test them, he forgot to take the landing into consideration, with disastrous results.
"AAAAAAARRRRRRGGGGGGGGGGGGGGGGGGGG!!!!!! WAAAAAAAOOOOOOOOOOAAAAAAAAAGGGHHHHHH!!!!!"
This guy is the first person you see outside of the tutorial town, falling from the sky. There is no associated quest or follow-up.
It's an instantly memorable encounter. A non sequitur punchline to the Grimy Medieval Fantasy the game set up for the last ten minutes. And it also teases the over-the-top magic mechanics; you can take his scrolls and try Acrobatics 1000 for yourself right off the bat.
Every time I replay Morrowind, this catches me by surprise and I burst out laughing. Then I take his silly hat and robes, pawn off the rest and set off for Balmora.