White flag

A white flag was a symbol of truce during war, meaning the individual or party waving the flag should not be attacked. The Seventh Doctor claimed the flag was a symbol of truce throughout the civilised universe. However, Gavrok of the Bannermen shot the flag when the Doctor waved it. (TV: Delta and the Bannermen)

Within the Torchwood Tower in 2007, the Tenth Doctor held a sheet of A4 paper on a stick as "surrender[ed]" to a group of Cybermen, jokingly apologising for not having an actual white flag. (TV: Doomsday)