But some of the most delightful bits come from Raj (Kunal Nayyar), the show's remaining singleton, whose ambiguous sexuality flavors everything he says. Nayyar's performance grows increasingly charming, as does Bialik's; in addition to her grappling with Sheldon's impermeable narcissism, the strange undercurrent of lust in Amy's friendship with Penny stirs up comic anxiety. And of course Sheldon never fails to delight as, among other things, he lets all his decisions be determined by a roll of the dice; treats Leonard as "Schrödinger's Friend"; and embraces chaos in his life by playing bongos in the middle of the night and wearing Tuesday pajamas on Thursday night. All in all, though season five feels less surprising than previous seasons, the quality of the writing and performances remains high. The extras on The Big Bang Theory: The Complete Fifth Season are unremarkable, except for a featurette about the series' director and designers, which shows a different side of network television. Guest appearances included the recurring Wil Wheaton, Brent Spiner, Stephen Hawking, and a vocal performance by Leonard Nimoy as Sheldon's conscience. --Bret Fetzer