And two of my favorite male characters in game are Sith purebloods. You encounter both if you play a Jedi-knight.
First there is Lord Praven, you meet him on Tatooine and once you defeat him you can opt for two choices, kill him or persuade him to become a Jedi.



What I absolutely loved is that if you have him see the light and turn to be a Jedi. He sends you a blue color crystal for your lightsaber. And not just that you get to meet him again, in your last class quest line on Corellia. I highly suggest to use Lord Scourge as your companion for that scene because they sort of have a little pissing contest. I love their attitude towards each other. Had me really giggle like some teenage girl. ;D
Which brings me to my other favorite Sith pureblood... Lord Scourge:


If you are into playing full light side, be prepared to have a couple of trophy companion gifts stored somewhere, because Lord Scourge might give you a headache every time you give a certain answer he dislikes.
For example:
+15 T7
+17 Kira
+55 Sergant Rusk
+40 Doc
-728 Lord Scourge
;D
On the other hand he's easy to gain affection with if you are playing your Jedi-knight dark. Still... watch your answers, on Corellia I managed to get 2 times over -500 affection with him.
For those who don't care about the affection, I highly suggest to take him along for certain quests. He's got the most amazing answers sometimes. I really adore him.




Of course you encounter more Sith purebloods like Krannus on Belsavis:


Last but not least, if I were to play a male Sith pureblood my character would look like this:


And with that I close this rather girly post but hey, I do enjoy some eyecandy in game. ;D
Edit: Oh boy, there were tons of repetition and other mistakes in this post. Just re-read it and edited a lot of stuff out. I shouldn't write entries when I just crawled out of bed, my brain apparently needs some time before it's fully functioning.