"Scourge of the Galaxy" was a phrase applied to various evils in passing, depending on what galaxy was being mentioned.
The Argolin were said to be the scourge of the galaxy before becoming tourist guides for the Leisure Hive. (PROSE: Doctor Who and the Leisure Hive)
Frobisher claimed that the Whifferdill were the Scourge of the Galaxy. (COMIC: The Shape Shifter)
Geralk said the Cybermen used to be the Scourge of the Galaxy. (AUDIO: Return to Telos)
The Tenth Doctor later called Baltazar the Scourge of the Galaxy, (TV: The Infinite Quest) and applied the same title to the Macra in M87. (TV: Gridlock)