Bad Grandpa .5 gives you a whole new perspective on the world of Irving Zisman with bonus scenes and pranks also featuring Spike Jonze as "Gloria" and Catherine Keener as Irving's wife "Ellie", plus a look at the evolution of Johnny Knoxville's naughty alter-ego, the makeup effects, and a behind-the-scenes peek at the idiocy it takes to make a hidden camera movie in public.
| Actor | Role |
|---|---|
 Johnny KnoxvilleIrving Zisman / Self | Irving Zisman / Self |
 Spike JonzeGloria / Self | Gloria / Self |
 Jackson NicollBilly | Billy |
 Catherine KeenerEllie / Self | Ellie / Self |
 Georgina CatesKimmie | Kimmie |
 Zia HarrisChuck | Chuck |
 Jeff TremaineSelf | Self |
 Trip TaylorSelf | Self |
 Dimitry ElyashkevichSelf | Self |
| JJ.P. BlackmonJxPx Blackmon | JxPx Blackmon |
 Rick KosickSelf | Self |
 Jack PolickSelf | Self |
| CCarl WattsTSA passenger | TSA passenger |
 Tony GardnerSelf | Self |
| SSteve ProutySelf | Self |
| KKnate GwaltneySelf | Self |
| CCharles GrishamSelf | Self |
| JJoe “Oz" OsborneSelf | Self |
| DDonny AndersonSelf | Self |
| AAndrew LaboySelf | Self |
| HHeather BrownSelf | Self |
| TTom HeiglSelf | Self |
 Seamus FrawleySelf | Self |
| DDerek FredaSelf | Self |
| CChristopher SmileySelf | Self |