From TARDIS Index File, the free Doctor Who reference.

For the short story with the same name in More Short Trips see here.

Scientific advisor was the title given by UNIT to their personal adviser on science and technology-related matters. In the 1970s, the British branch of UNIT originally selected Liz Shaw to be their scientific advisor, but this role soon went to the Doctor, with Liz staying on as his assistant. (DW: Spearhead from Space) The Doctor served as UNIT's scientific advisor throughout his exile on Earth.

By 2010, UNIT's scientific advisor was Malcolm Taylor. (DW: Planet of the Dead)

Parallel Worlds

In a parallel universe, the Master served as UNIT's scientific advisor. (DWU: Sympathy for the Devil)