Season 1 collects “Metamorphosis” for Metamorpho’s origin story. Season 1 collects the following episodes:

• Metamorphosis – Collects Episodes 22-23 of Part I-II

Despite being a historic character, he has remained a C-character. When he joined the JLU, he was relegated as a background character.

During “Hereafter,” Superman seemingly dies after Toyman attacks him. During his absence, the JL briefly considers Metamorpho as a replacement, showing he is a V.I.P.

Metamorpho is mentioned in Season 2, Episodes 19-20 which collect “Hereafter” Part I and II.

When the JLU forms, Metamorpho becomes a reserve member they call during times of crisis. Often, he is a background character not shown in fights.

He makes appearances in the following episodes: “Initiation”, “Clash”, “Question Authority”, “Panic in the Sky”, “Divided We Fall”, “Alive!”, “Destroyer”.

Rex Mason is an archeologist, who became a metahuman superhero known as Metamorpho, capable of transmuting elements in his body into various forms.^[1] Mason was kept in Lex Luthor‘s Pocket Universe, binded by Luthor’s kidnapping of his son Joey. Luthor aimed to use Mason’s transmutational powers to imitate the extra-terrestrial element Kryptonite and keep Superman imprisoned. ^[2]

-Metamorpho, DC Universe Wiki