While I agree, that it's debatable, I found the Gray Fox to be a very unmemorable character. I liked the mystery surrounding him, but the person himself was... well, in my opinion, lame

Well he is one of the main icons of the Thieves Guild.

Perhaps his personality is not that memorable but the character as a whole is really memorable. Just think about it, the Grey Fox...

Ulfric <-----sixy as hell

Paathurnax

Arngeir

Cicero <---he scares me.

Stab, stab, stab, stab, stab. And then. Stab, stab, stab, stab, stab Love that guy. If only he wasn't such a mama's boy

Arngeir
Hadvar
M'aiq
Ysolda
Mjoll the Lioness
Alvor (although he dies too easily whenever a dragon attacks Riverwood)
The Companions

Characters who are memorable in a *bad* way:
Ulfric
Braith
Nazeem

Tim (aka the Slipperman)

The guard. Just because of his foreigny voice.

No one else.

Maybe Lydia...

300 hours in and have not met a interesting character yet and not sure i will.Then again i am holding the side characters to the likes of Alister,Morrigan from DA! or Vernon Roche or king Henselt from The Wicther 2 and it is light at day.It seems they completely forgot about side characters to me.

Good
- Paarthunax
- Cicero
- Babette
- Sheograth

Bad
- Ulfric
- Belethor
- NAZEEM

Paarthurnax
Delphine
Esbern
Malborn
Elenwen
Ancano
Ulfric
Jarl Balgruuf
Cicero
Arngeir
Ondolemar
Lydia

Arngeir aka Christopher Plummer

Galmar Stone-fist because of the epic viking feel to him
Nazeem because of all the ways i have butchered him in the streets of whiterun (usually on my first visit there)
Sheogorath Because of the fishstick
And Paarthurnax for obvious reasons

I have to bring up Anska, she would be a great follower (once she starts not casting AOE spells )

cicero and erandur comes to mind

There are not enough of them considering the size of the game. But these are the few I've found that have been interesting to me and help keep me playing the game.

The guards: Due to her voice (it's so cute) and acting my favorite is the female one since they all say the same things.
The followers: Whoever worked on them did a good job with giving some of them distinctive personalities. The ones I've had time to spend with and like the most are Marcurio, Jenassa and Erik the Slayer. The biggest downfall about all three of these is their voice actors do too many other characters in the game.

General Tullius and Legate Rikke - I enjoyed them the most when they were together and trading dialogue with each other.

Jarl Balgruuf - He's so awesomely Jarl-y.

great question, for me it would be faendal...just cause i was new to the massive world of skyrim and right off the bat i had a buddy/companion, easier and safer, skyrims alittle overwhelming at first.

I don't think Cicero, babbete or Sheo are good people xD