Rex Mason aka Metamorpho is one of the supporting protagonists in Batman: The Brave and the Bold.
He is voiced by Scott Menville.
Rex Mason was only a teenager when he was hired evil industrialist, Simon Stagg to help locate the Orb of Ra in Egypt. When Mason succeeded, Stagg's assistant Java betrayed him. Left for dead in the light of a meteor, Mason survived and was transformed into a oddity. Calling himself Metamorpho, the Elemant Man, Mason traveled the world seeking a cure for his condition.
Metamorpho was eventually recruited by Slug into the Outsiders. It seems likely that Slug appealed to Metamorpho's obsession with eating rather than ideology. Because of his child-like innocence, Metamorpho often depends on his friends, Black Lightning and Katana, as a moral compass. Likewise, when they turned on Slug and saved Wildcat, Metamorpho followed suit. Metamorpho is one the few fans of Wildcat's Tiger Tonic drink.
Despite having a happy-go-lucky personality, Metamorpho hid his fear of being a freak. It was exposed when Psycho Pirate kidnapped the Outsiders and fed on their rage. Metamorpho's was the strongest and used as Psycho Pirate's source of power while Batman was distracted with saving Katana and Black Lightning. As the duo reasoned with Metamorpho, Batman attacked Psycho Pirate and defeated him.
Metamorpho was implanted with a Starro clone by Faceless Hunter. After the siege of Starro, Metamorpho and the rest of the Outsiders joined Batman in a mission against the Kobra Cult as they attempted to usher Kali Yuga. In the battle's aftermath, Metamorpho knocked out Kobra's leader, Lord Naga, by shaping one of his hands into a mallet.
- The Power of Shazam! (cameo)
- The Siege of Starro!, Part One
- The Siege of Starro!, Part Two
- Requiem for a Scarlet Speedster!