I thought Season 1 had some great performances by characters who were killed off or didn't appear again: Mikey Palmice, Master P, the soccer coach on Meadow's team, and Pork Chop Boy Jimmy Altieri.
Massive Genius, aka "Massive G", played by Bokeem Woodbine. He was in a few so-so '90s hood flicks. Finally hit the big time just last year as Mike Milligan in Fargo.
Massive G was a great role. It's too bad Woodbine's career didn't take off after that. Despite the obvious animosity between the mafia and blacks, you got the feeling that Tony's crew actually liked G, sans probably Paulie. He understood business, believed in making money for everyone and gave the impression he would kill if he had to. Just imagine him being Italian and not black. Tony would have brought him in and probably put him above Chrissy.