Felix Nash is the main antagonist of Ernest Goes to Jail. Despite the comedic nature of the Ernest series he was actually a rather fearsome adversary, though like most comedy villains he was defeated by the titular Ernest and made to pay for his many crimes.
He was portrayed by the late Jim Varney.
Felix Nash was a convicted crime lord on death row who also happened to look identical to Ernest, this would allow Rubin Bartlett (one of Felix’s cell mates) to come up with a plan to have Felix switch places with Ernest and evade death row while having Ernest falsely imprisoned so as to fool the guards into believing Felix was still in prison.
As Ernest tried to reform the prisoners in his own eccentric (but well-meaning) way, Felix proceeded to try and live Ernest's life but was angered at the way people dismissed him and believed he was doing Ernest a favor when he started commiting mean-spirited acts and criminal behavior that alienated him from Ernest's friends.
Ultimately Felix masterminded a plan to rob Ernest's own employers, who just so happened to be a rather prominent bank, yet Lyle (Felix's other cell mate) grew attached to Ernest and felt guilt over letting an innocent man die just so Felix could further his own criminal lifestyle, which ultimately resulted in Ernest escaping prison. Rubin tries to stop Ernest from escaping the prison at its gate, but Lyle tells him to spare Ernest. After knocking out Rubin, Lyle releases Ernest who tells him goodbye afterwards. Ernest engages Felix in a battle after arriving at the bank. After Ernest is electrocuted by Nash, he regains his superpowers that previously helped him escape prison and flies through the bank skylight with the bomb and is seemingly killed when it explodes. As the bank employees mourn, Nash holds them at gunpoint but is ultimately defeated when a burned Ernest crashes back through the skylight and falls on top of Nash, leading to his arrest.