Dalek Antibodies are minor antagonists that appear in the Doctor Who episode "Into the Dalek". They are sphere-like robots who live inside the casing of a Dalek and are responsible for destroying any foreign bodies inside the Dalek.
They appear three times in the episode, the first time they appear is after a soldier named Ross set a grip hook inside a Dalek nicknamed "Rusty" where he along with another soldier named Gretchen Carlisle, a resistance fighter named Journey Blue, The Twelfth Doctor and his companion Clara Oswald were investigating why the Dalek had turned good. The antibodies surrounded Ross and killed him, but the others are able to escape.
They later appear when the group plan to turn Rusty good again so the Doctor goes to the mutant whilst Clara and Journey go to the Dalek's memory banks but in the process, Gretchen is killed by the antibodies whilst putting up another griphook.
The antibodies are last seen pursuing Clara and Journey but leave once Clara awakens Rusty's memories.