Stephen (Attack of the Space Leeches!)
From Tardis Wiki, the free Doctor Who reference
Stephen was a young boy with a cold when Space Leeches crashed a ship near Primrose Hill, London in April 2010.
The TARDIS materialised around him and the Eleventh Doctor manufactured a highly infectious virus from Stephen's cold virus that weakened the space leeches' hold over people.
The Doctor assured Stephen he would take them to a safe place. (COMIC: Attack of the Space Leeches)