But make no mistake: Jim Parsons, as Sheldon, drives the show. With Leonard (Johnny Galecki) and Penny (Kaley Cuoco) grappling with fairly conventional relationship issues, it falls to Sheldon to turn every potential cliché into an opportunity for unexpected lunacy. His combination of ruthless rationality, profound narcissism, and yawning neediness make Sheldon a remarkable comic creation, and Parsons plays him to the hilt. Even funnier than his relentless analytical approach to emotions is when he tries to be more human; his attempts to comfort Penny when she's injured are hilariously unnerving. Watching Sheldon "grow" over the course of The Big Bang Theory's progress is one of the show's greatest pleasures. --Bret Fetzer