<Li> Justice Leak as Hellgrammite: An alien escapee from Fort Rozz who feeds on DDT, and is later killed by Alex . Based on the DC Comics character of the same name . </Li> <Li> Chris Browning as Ben Krull / Reactron: A former nuclear physicist and an enemy of Superman who decides to get revenge on him by trying to kill Supergirl as payback for his wife's death . </Li> <Li> Levi Miller as Carter Grant: The son of Cat Grant, he is sensitive and shy and has a crush on Supergirl, which he confesses to Kara when she babysits him . </Li> <Li> Iddo Goldberg as T.O. Morrow and Red Tornado: A brilliant scientist, and his android designed as the ultimate super-weapon that gains sentience . Morrow later reprograms Red Tornado to kill Kryptonians, and both are defeated by Alex and Kara, respectively . </Li>

Who plays cat grant's son on supergirl