1. No two characters of the same franchise
2. Online Freeware and self-created material doesn't count

NOTE: might include spoilers, as well as that I don't play many games

5 - Klungo (Banjo Tooie)

He gets a dramatic cutscene for his intro and only fights you with potion effects that are annoying. Rank 5 as it's fun to watch him go away, expecting to get beaten up by Gruntilda.

4 - Kaepora Gaebora (Ocarina of Time)

He's annoying. He constantly informs about things I don't care for and take forever to finish his speech. And, if you were skipping through the text, you might make him do his speech AGAIN. Although he was helpful on top of the death mountain, thus making him only rank 4.

3 - Megaman (Megaman Series)

One of the most stupid player characters. Not just that he looks silly (In the NES games), he has awkward controls and is stupidly slow, which makes every level a pain in the ass. Rank 3 as he is slightly better in the X series.

2 - Lord Lucien (Fable 2)

An annoying bastard who kills your entire family and turns out to be a complete wimp in the end. Not much to say here.

1 - Reimu Hakurei (Touhou)

The most despisable character I've ever found. She abuses the Spell Card System and the Border of Gensokyo to not just win about every battle, but ensure that you never get a chance to retailate. Also, the universe bends around her needs - victorious enemies surrender, she gets to celebration after trying to (with some flunkies) take over the moon, going to stupid things as fish forming a brigde for her to cross a river. In short, the most blatant Mary Sue in the history of fiction.

Characters barely missing the list:

(don't know his english name) (Yoshi's Story)
A huge elephant who devoted his life to block your way. No rank since he's too easy to avoid.

Nue Houjuu (Touhou)
Well, basically, she's just too silly to be taken serious. The common reasons for her being bad (Ripoff issues, Stupid look) don't bother me much.

Navi (Ocarina of Time)
Similarly annoying as the owl, but stops you far less often and also works as your aimbot, making her a fairly useful helper.

Captain Quark (Ratchet and Clank)
Comes to "fight" the boss you on to, but only after you're done to take the credit for it. He is helplessly hilarious, though, dampening on rank 6 or 7 or so.