Dexter

Dexter Morgan is a forensics at Miami Metro Homicide, seemingly living an ordinary life.

On his sparetime, he goes vigilante upon assholes deserving it, whacking them mercilessly, and dumping their chopped up corpses into the ocean.

This fictional character is by no means portrayed sympatheticly, at least not initially, but he grows as a person as the series goes by.

The Dexter we leave in season 8, the last one, is by no standards the same person as in the first seasons.

It's not enough forensics working around in the world to make someone like Dexter very likely in real life.

Still, one have to admit, a vigilante like Dexter is absolute possible.

A vigilante using tricks from forensics to cover his tracks, is ofcourse very much within the realms of possibilities.

However, a vigilante outside forensics would have a hard time gathering sufficient evidence.

Even thou Dexter is a coldhearted killer, he seldom misses his mark when it comes down to justice.

Dexter never kills an innocent on purpose.

He lives by a code invented by his father.

And he kills by the same code.