Characters I need more information about to 'classify'  

John Constantine from Constantine
Ivanhoe
Alan Breck Stuart in Robert Louis Stevenson's "Kidnapped" and "Catriona" novels (author of Treasure Island)
Major Charles Emerson Winchester III (M.A.S.H.)
Jean-Francois (from Brotherhood of the wolves) ??
Heroes of Byron's works

and

Lady Claudia: I'll keep this here since it is an interesting view and cross between Dracula/Heathcliff and an unfeeling logical man, M'Choakumchild. Though I have no clue if he is a good or a bad guy, hence reformed or not, let's keep this anyway.  

From the reporter

Snape has the characteristics of two conflicting personalities: 

Dicken's Master M'Choakumchild, the unfeeling fact-oriented teacher whose methods "grind" out students, eradicating all emotion and imagination;

Mr. M'Choakumchild (from this web site)

The teacher Mr. M'Choakumchild is essentially a briefly seen caricature, as indicated by his unrealistic name, but aspects of his name and personality refer to contemporary figures and philosophical debates. The Scottish "M'" (more familiarly rendered as "Mc") at the beginning of his name underscores the degree to which educational theory at the time, as well as Utilitarian thought, was derived from Scottish thinkers.

Moreover, Dickens may have had two Scotsmen—both named McCulloch—in mind as loose models when he chose the name. The lesser-known, J.M.M. M'Culloch, was a headmaster at an Edinburgh school and wrote practical and dry textbooks. The second, J. R. McCulloch, was a well-known political economist and statistician. In the wake of the public dismay after the publication of Thomas Malthus's Essay on the Principle of Population (1806), McCulloch "embarked on a lifelong campaign to improve the public image of political economy," according to Mary Poovey in A History of the Modern Fact. Poovey continues:

By rewriting the history of the discipline, creating a canon for political economy, making reliable texts of the Wealth of Nations available for the first time, and placing political economy at the center of countless educational schemes, McCulloch sought to popularize the science that Malthus had rendered so disagreeable. McCulloch was not completely successful in resuscitating political economy, of course; opponents of the manufacturing system, like Dickens and Carlyle, simply turned their venom from Malthus to McCulloch and continued to lament the end of moral knowledge.

Dracula/Heathcliff, the Byronic hero, dark, mysterious underdog who is misunderstood and mistreated, and in turn, mistreats others. 

James *Logan* Howlett

X-Men comics

 Lady Claudia: Yes, he's a dark brooding character but he doesn't have the finesse of Snape and he's not as clever as he is. I could say he is more like a roguish street-guy version of Snape if ever there was one. However, if Snape was indeed in love with Lily, then his character would prove closer because Wolverine is madly in love with Jane... who is in love with the handsome Peter, the James-Potter version in the X-Men.

On Wikipedia

Maurice LeBlanc's books

Lady Claudia: I find him more like Robin Hood than Snape but I can understand why many would place him here.  His cleverness is legendary and he's a thief still. There's no reform to him since he steals from those 'who deserve it' so that also works though I always got the impression he was too much extraverted in his manners, not brooding or reserved, especially with women!

On Wikipedia

From reporter:  He's intelligent and clever. He has his own view of the world. He's a dark character but yet a gentleman. He is obsessed with perfection and planning... He is in his own side (not evil/not good). He only acts when he's in control of the situation...

from Homicide: Life on the Streets and Law & Order SVU

On Wikipedia: "Munch has been described as a stubborn man who can "smell conspiracy from a five-year-old's lemonade stand." Munch's cynical facade has occasionally slipped, however, revealing a deep compassion that developed from his unhappy childhood. Munch's investigative style is based around a meticulous attention to detail"

From reporter:

I find him irresistable sexy, but snarky and closed off, unless he's defending his favorite thing;

from Melville's
"Billy Budd"

From Reporter:

he is a bit like Snape. His position on the ship is similar to Snape's at Hogwarts: he is an officer and a kind of chef of the ship police.

Apperance:

slim, pale, black hair, about 35 years.

Character & so on:

He is introverted, follows the rules, is secretive, subtle, educated, very intelligent, no one knows his past, he is unpopular, severe, very proud, melancholic, bitter, very self-possessed. People laugh at him but they are afraid of him. He envies Billy (a young sailor) his popularity and happy nature, and at the same time he feels disdain for Bill's naivety. He is obsessed with hate (and love?) for Bill.

of Greek mythology

On Wikipedia

From reporter:

 Hades has been widely misunderstood and accused as a rapist.  These accusations are in my opinion false; he is rather a seducer in the way that all things dark and occult are seductive.  Hades steals Spring to enable the souls of the dead to be reborn into the living.  He does this by offering Spring the identity of Queen of the Underworld. 

 If you were to ask a believer in archetypes, he/she might say that these archetypes lie so deep within the mind that even author Rowling may not be consciously aware she is drawing upon them.

The character is important, as is the recognition of House Slytherin, because it reassures the reader that these aspects which live in each one of us do not make us unacceptable as human beings.  Far from it.  Young readers learn that even though they have emotions, thoughts, dreams, imaginations, etc., which are dark and dreadful, these are still important, and still fuel stories and power sorcery.  One might casually say, "House Slytherin?  Oh, all the Evil Witches come from there," and let it go; That's way too simple.  Snape's task as faculty advisor to this House to take this understanding of darkness and transform these students into fierce guardians of right like him. (Snape really is quite a guard-dog in the third film)  To succumb to evil purposes is weakness; to understand the vulnerability which might lead down that path is to have a chance of preventing it;  Snape has got quite a job...

Gannish

from the Comic Crossgen, The First

From reporter:

He is a Mage
People do not trust him. Mostly the house of Dexter do not trust him.
He is know the true before others. and he suffer a lot to keep the truth.
Do not trust people only he trusts Yala his lover from the other House
Keeps very quiet
Bad Attitude
Disturbed
Dark
Ruthless
Loyal
This is a Drawing on him that I draw from the comic
http://www.pbase.com/image/19796009

Hauke Haien

by Theodor Storm

Lady Claudia: I searched for info in English but it's very scarce. Nothing on the character himself.  But I  found this e-book at Bartleby. I didn't read it but for anyone interested, it's here!

From the reporter:

He has some very snape-typical traits, for example he is estimated older than he is because acts so much mature. He also didn’t fit with people his age, not even in his youth because he is very intelligent and studious- he worked out how to improve the stability of dikes all by himself when he was young.

He is misunderstood by most people in the village. That’s because the story’s mostly about a modern thinking person,  whose tragedy is to live in a time and environment that couldn’t understand him.(Perhaps it’s important to know that the story is set in mid-18th century, written at the end of 19th century to understand that). And just to prove that I didn’t mean that snappish characters couldn’t be nice, this one actually is. Not only has he a strong sense of justice and very firm values. Hauke  even is much kinder than most of his fellow men: He loves his wife and his daughter dearly although the kid is a bit retarded. He saves this little dog from death and buys and coddles up this mistreated white horse. However these very actions are not understandable to the villagers because in this time they were so superstitious. There are rumours that the horse is inhabited by devil and the stray dog was meant to be buried alive in the foundations of a new dike, which is believed to break without ‘something living’ being sacrificed. Hauke’s reaction toward these rumours, partly even hostilities toward his person, is also very Snape-like. He develops his own mistrust against the rest of the village and assumes only the worst of them. For examples when he hears about the rumours he imagines them much worse than they actually are, just how Snape expects the worst of everyone else (most visible after the Pensieve-scene, when he thinks Harry enjoyed seeing him humiliated). To conclude, Hauke feels in hated and rejected by anyone else except his family and that  makes him bitter and lonely, which is also very snapish, I think. Wow, sorry, that was a lot and I don’t know if everything was necessary, but I thought you should get a thorough picture of this character… but perhaps I got a bit carried away, I wouldn’t have thought I’d busy myself with this book again, as I didn’t like it too much at school. And now I find it’s actually  interesting… :-P

Lord Byron
(1788 – 1824)

Historical figure: mainly novel author

On Wikipedia

From the reporter:

His romantic personality. With this I of course do not mean ‘pink cloud around your head’ feeling, but the deep sense of  weltschmerz (the most brilliant word in the German language and utterly untranslatable, but is means a kind of  soul-ache and melancholy when beholding the world around you) of the true romantic nature.
This romantic tendency expresses itself in his fondness of Newstead Abbey, the very ‘gothic’ and ruined abbey where Byron and his mother lived in his youth. Also his fascination with Greece, Albania (which was and probably still is the most imaginative, violent, sinister and problematic region in Europe) and the vanished glory of Venice testify of this. His nature was certainly not passive – he actually fought in the Greek independence war against the Turks.
His friendship with equally unorthodox types like Scott, Shelley and Hobhouse.
His love-life, which was everything except dull. If he fell in love with a woman, even her married status was nothing of a hindrance for him. He cared nothing for socially acceptable behaviour, but acted according to his own judgement, not always tempered by reason.
His family background. Old and distinguished. The first mention of the Byron family goes back as far as the Domesdaybook (1086-’87), in which there is mention of one  Ralph de Burun from Nottinghamshire (died 1156).

Fjodor Dostojevsky book (Russian novel masterpiece)

From Wikipedia:

"Is the middle son and first by Fyodor's second marriage. He is a fervent rationalist and atheist, disturbed especially by the apparently senseless suffering in the world. As he says to Alyosha in the chapter "Rebellion" (Bk. 5, Ch. 4), "It's not God that I don't accept, Alyosha, only I most respectfully return him the ticket [to salvation]."

From an early age Ivan was sullen and isolated from everyone around him. He carries a hatred for his father that is not openly expressed but which leads to his own moral guilt over Fyodor's murder and contributes to his later insanity. Some of the most memorable and acclaimed passages of the novel involve Ivan, including the chapter "Rebellion," his "poem" The Grand Inquisitor immediately following, and his nightmare of the devil (Bk. 11, Ch. 9)."

From the reporter:
Most interesting is the conversation with his brother Alekej (part II, book V) in which speak about good and evil. This also includes the must-read chapter in which Ivan tells his brother the story about Christ and the Inquisitor.

Ivan is very honest and sarcastic.
He is a sharp observer of the things that happen in the world, and has a clear judgment over it.
He is fascinated by the darker side of people, and the nature of power, dominance, control over others, etc.
Still, he seems to be truly concerned about the ones at the bottom of society. He feels genuine pity for them, even in his own sarcastic way.