The most Memorable Character in all of literature?

Here are my few memorable characters.

Mephistophilis - Doctor Faustus
Dorian Gray - The Picture of Dorian Gray
Heathcliff - Wuthering Heights
Joe Gargery - Great Expectations
Levin - Anna Karenina
Billy Buck - The Red Pony
Bathsheba Everdene - Far from the Madding Crowd
Emma - Emma

well my choices have been mentioned but Raskolnikov, Humbert Humbert and Levin.
I dont know if you want to read the whole Karenina novel if you are just studying characters. I think that Anna was good but in comparison to the all time great characters of prose, she doesnt really live up. Levin is really excellent though.
I think Raskolnikov (or almost any of the main characters in Dostoevskys famous works) and Humbert Humbert are must reads for studying characters.
For various reasons not as many female characters have been mentioned, its really tough me for me to pinpoint truly amazing female characters off the top of my head. Maybe Elizabeth Bennett?

Dunya in Crime and Punishment.

Since this is an individual question, I will answer individually.

The way I read I place myself in the novel. This means that I can hear, see, smell, touch, and sense things as one of the characters themselves. This makes nearly every protagonist and antagonist in every book memorable to me, so long as the work is worth the cost of admission.

There are, however, characters who remain with me and on whom my life is based. This may sound weird, since we are talking about fiction, but some characters are good. And since it is fiction, they can be good to the point of obsurdity.

Sam Damon and Ben Krisler from Once an Eagle, Gus McCrae and Cpt Call from Lonesome Dove are my main for good guy characters

Long John Silver from Treasure Island and Courtney Massengale from Once an Eagle (I love that book. It is the only one I read at least once a year) are my antithesis characters. In fact, if I call someone a "Massengale" or "Courtney" there is no higher insult, though most people don't get it.

For readers, I imagine Legolas, Gimli, Aragorn, Hector, Achilles, Candide, Dr. Jekyll, and Winston would be memorable. (List incomplete)

the book with the most interesting characters of all time has to be catch 22. although all are not all looked at in depth, they are the most unique characters in literature.
certainly yossarian is tops
but what about
milo minderbender--the worlds greatest entrepreneur
major major major major--he was only in when he was out
the soldier in white--just switch the drip from out to in
mcwatt
snowden
doc deneka
dunbar
nately
nately's whore
the chaplain
wintergreen

i could go on. almost every character in the book is fascinating and unique. sometimes it is who are they which can be just as interesting as what are they.
not a character study, but a study of characters!

Memorable characters from literature can mean characters whose everything we remember vividly far after years and years of reading the book. There have been quite a few of such characters the whole world have wept with, heartily laughed with and profoundly thought with. The first to come to mind is Jesus Christ, the saviour of human soul. Even though a compilation, The Bible is a great literary creation full of many more memorable characters including Moses, Lazarus, Mary, Magdelena, Yohannan, Peter and of course Judas. Victor Hugo's Jean Val Jean was the first character the world properly wept with. And the world heartily laughed with Cervantes' Don Quixote and Sancha Panza. Elizabeth and Darcy were whom the world once wanted to be. Brahm Stoker's Count of Dracula still haunts the world. Raskol Nikoff's inner sufferings still crushes the heart. Arthur Conan Doyle's Sherlock Holmes is a universal thrill. Charles Dickens' portrayal of his characters was like making a full-length film. Oliver Twist and Faggin and Bumble and Bill Sikes will never go from this world. The most playful character the world saw was Mahabharatha's Krishna. Odessius and Herculis stand like lone pillars erected against time by Homer. And The Vicar of Wakefield, The Mayor of Castorbridge, The Count of Montichristo, The Hunchback of Notredam, Ivan Illyicch and Silas Marner will always be with us.

As far as philosophisers go:
Kashiwagi - The Temple Of The Golden Pavillion
Zeitblom - Doctor Faustus
Oskar- The Tin Drum

Richard III should get a mention.

Characters from David Copperfield and Mill on the Floss.

Memorable ot me means public awareness to the point where even if the book has NOT been read a person knows 'something' about it--therefore I present Sherlock Holmes, Frankenstein, Dracula and Tarzan of the Apes. Hamlet but only for the To Be or Not to Be speech.

Ahab of course

It's still Jesus.

Anthony Powell invented many great characters in his Dance to the Music of Time series, but the most outstanding were Kenneth Widmerpool, Charles Stringham and Pamela Flitton/Widmerpool.

I used to love Captain Call from the Lonesome Dove series.

Having recently read Great Expectations I would nominate Lady Havisham and Estella for hard as nails female characters; and Tess Durbeyfield from Tess of the d'Urbervilles, who I am reading about now and who is as tough as nails in her own way.

One of my favourites is Claude Frollo from Hugo's Hunchback of Notre Dame. His scheming, passionate and diabolical character remains one of the most memorable to me.

Humbert Humbert and the girl are definitely strong characters.

But the first things that came into my mind were Anthony Blanche and Sebastian Flyte from Brideshead Revisited. Especially because the actors in the tv adaption look just like how one would imagine the characters to look.