Ecktosca Fel-Fotch Heppen-Bar Slitheen was a member of the Slitheen family in the 26th century. He was a prisoner in the interplanetary prison of Justicia alongside his brother Dram. When their distant cousins and enemies the Blathereen tried to take over Justicia they along with their Aunt Callis (who had broken in to Justicia to find them) helped the Ninth Doctor defeat them.
Ecktosca and Callis faked their deaths and hid in the bodies of the dead Blathereen leader Don Arco and a Blathereen technician, they then reunited with Dram and planned to use the Blathereen gravity warp technology to kick-start the Slitheen family's return to crime. (PROSE: The Monsters Inside)