Codal

Codal was a member of the Thal taskforce sent to Spiridon to defeat the Daleks based there.

Biography
Codal was the team's scientific specialist, and was particularly investigating the Dalek's ability to become invisible. He was once captured by the Daleks, and spent time in a prisoner holding cell with the Third Doctor. There, the two had a long discussion about the nature of bravery. Codal felt that he was bereft of that quality, but the Doctor seemed to convince him that he in fact was possessed of great courage. (DW: Planet of the Daleks)