4. Bubbles
It was a wonderful journey watching Bubbles play so many roles; struggling addict, caring uncle, informant, your friendly neighborhood depot (via shopping cart), and newspaper slinger. Bubbles was an essential part of the major crimes unit, his vast knowledge of the streets and crafty trick of identifying people with his red hats was invaluable to Kima and the gang. And he is the only one who got to say "McNutty". Bubbles was sort of the biblical Job of The Wire. Everything bad happened to him. His best friend and "business" partner overdosed in Hamsterdam, he was the victim of street bullying (he literally was beaten to a pulp and robbed almost every day), and when he finally had the back-up to take care of that problem via Herc, things went wrong. Then of course, his plan to kill the bully went horribly wrong when his nephew accidentally tried to get high off the poison. This all lead to a failed suicide attempt and ultimately, an introspective and sober Bubbles, who wins back his sister's trust at the end of it all.