Smallville (2001)

S4E6 Transference

Clark feels an irresistible pull towards the state penitentiary, lured by a kryptonian crystal that Lionel is wielding to swap bodies with Lex. Just in time, Clark steps in, leading to Lionel inhabiting Clark's body instead. With his new superpowers, Lionel sets out to reclaim his wealth and drive a wedge between Clark and his friends. Meanwhile, Clark must prove his true identity to his parents and find a way to reverse the body swap, all while dodging dangerous inmates who threaten his life.