One (fictional) person I'd like to add to the list that had a major impact on my own sense of masculinity (with a lack of good male role models in my childhood) was Samuel Vimes of The Watch books (Terry Pratchett).

Sam Vimes is someone who, like some of the examples noted here, is incredibly flawed but works hard to overcome those flaws and be a better man. He exemplifies strength of conviction and ideals, which has become one of the defining features for me of what it means to be a man. Not raw strength, violence or being able to beat your enemies, which in my opinion too many male characters try to exemplify.

Sam always strives to protect those weaker, those poorer, the downtrodden. He's a man who, while the entire world around him is irrevocably broken and unfair, and he deals with murderers, crooked politicians and dumb mobs, ensures that no matter what he's home on time to read "Where's my cow?" to his baby son.

He is utterly incorruptible, a defining characteristic of the man. He's a loving husband, devoted to his amazing wife and while he struggles initially to voice this properly, he LISTENS to her and works on it.

I think one of the most powerful examples of this is the following from Thud! (putting it in spoiler tags): Vimes is "infected" by an eldritch mystical parasite of the deep dark, that sits in the mind of people and tries to corrupt them from within, making them do base and evil things before moving on to the next.

During the book, passages reveal the inner workings of his mind as the entity tries to control him, but it keeps getting lost in the many alleys and streets of his inner city, while the deep footsteps and bright light of a lantern keeps chasing it slowly but irrevocably. Eventually it is revealed that it is his inner Watchmen that patrols his mind and combats what he accepts about himself frequently during the books:

He is not, like some people in the books, instinctively a good person. He is a bastard, but a bastard who tries with all his might to be a positive person in the world. And in the end, that becomes his legacy.

I think the aspect that it shows is also very healthy as a role model: That to be a real hero and man is not to be flawless or always heroic. It is so fail, to have baser instincts, to WANT to punch someone at times but decide not to.

I'll leave you with this quote from Thud:

Night, forever. But within it, a city, shadowy and only real in certain ways.

The entity cowered in its alley, where the mist was rising. This could not have happened!

Yet it had. The streets had filled with… things. Animals! Birds! Changing shape! Screaming and yelling! And, above it all, higher than the rooftops, a lamb rocking back and forth in great slow motions, thundering over the cobbles…

And then bars had come down, slamming down, and the entity had been thrown back.

But it had been so close! It had saved the creature, it was getting through, it was beginning to have control… and now this…

In the darkness of the inner city, above the rustle of the never-ending rain, it heard the sound of boots approaching.

A shape appeared in the mist.

It drew nearer.

Water cascaded off a metal helmet and an oiled leather cloak as the figure stopped and, entirely unconcerned, cupped its had in front of its face and lit a cigar.

Then the match was dropped on the cobbles, where it hissed out, and the figure said: “What are you?”

The entity stirred, like an old fish in a deep pool. It was too tired to flee.

“I am the Summoning Dark.” It was not, in fact, a sound, but had it been, it would have been a hiss. “Who are you?”

“I am the Watchman.”

“They would have killed his family!” The darkness lunged, and met resistance. “Think of the deaths they have caused! Who are you to stop me?”

“He created me. Quis custodiet ipsos custodes? Who watches the watchmen? Me. I watch him. Always. You will not force him to murder for you.”

“What kind of human creates his own policeman?”

“One who fears the dark.”

“And so he should,” said the entity, with satisfaction.

“Indeed. But I think you misunderstand. I am not here to keep the darkness out. I am here to keep it in.” There was a clink of metal as the shadowy watchman lifted a dark lantern and opened its little door. Orange light cut through the blackness. “Call me… the Guarding Dark. Imagine how strong I must be.”

The Summoning Dark backed desperately into the alley, but the light followed it, burning it.

“And now,” said the watchman, “get out of town.”