Blonde

Blonde was a hair colour. Several of the Doctor's companions were blonde, such as Rose Tyler, (TV: Father's Day) Chris Cwej (PROSE: Original Sin) and Romana. (TV: Destiny of the Daleks) After the Thousand Year War, all Thals had blonde hair. (TV: The Daleks, Planet of the Daleks) Karfelon androids were also all blonde. (TV: Timelash)

Blonde women in particular were specifically attractive to men. When Martha Jones asked Jack Harkness whether or not the Doctor "just [got] bored of us" and abandoned his companions after a while, he replied, "not if you're blonde", referring to Rose Tyler. Martha was aggravated with this. (TV: Utopia)

"Blonde" was also used as an insult to indicate stupidity. Esther Drummond was once asked, "How blonde are you?" when she attempted to leave the San Pedro Overflow Camp during a lockdown. (TV: The Middle Men)