Yes. The most infamous occasion happened in "The Daleks' Master Plan" at the end of the "Feast of Steven" Christmas episode when the Doctor wished the viewers at home a Merry Christmas. The Fourth Doctor addresses the audience in "The Invasion of Time". A character other than the Doctor continually speaks to the viewers in "The Caves of Androzani". Most recently, the Eleventh Doctor has broken the fourth wall at least twice: in "The Day of the Doctor" he looks right at the camera when Clara rides her motorbike into the TARDIS, and his "I'll never forget when the Doctor was me" farewell line in "The Time of the Doctor" is addressed directly at the camera, too..