On TV: Mos Def, LL Cool J, Common

Rap acts on television this week include Mos Def, who visits ‘Late Night with Conan O’Brien’ on Tuesday; LL Cool J, who visits ‘The Late Late Show with Craig Ferguson’ on Wednesday; Common, who performs on ‘The Tonight Show with Jay Leno’ on Friday; Gym Class Heroes, who perform on ‘Late Night with Conan O’Brien’ on Friday; and Spank Rock, who perform on ‘Jimmy Kimmel Live’ on Friday.