7. Attempted Assassination In "The Deadly Assassin"
Yes, I realize that the Doctor doesn't actually fire the shot that kills the President, and Chancellor Goth and the Master are really behind the whole thing, but the first episode is misleadingly directed in such a way to make the viewer to think that the 4th Doctor is a stone-cold killer with a sniper rifle, traumatising generations of children in the process. However, what I see as worse behavior from the Doctor is that in order to travel to Gallifrey alone, in the previous episode "The Hand Of Fear" he unceremoniously and brusquely dumps perhaps the most beloved series companion of all time, the utterly charming Sarah Jane Smith, in some anonymous suburban cul-de-sac nowhere near her actual home ("This isn't Hillview Road! I bet it isn't even South Croydon!"), with only a stuffed owl, some sad plastic flowers and a rather pathetic looking suitcase to keep her company. That plays like a jerk move in my book, seeming more like how Don Draper of Mad Men would treat an ex than what we expect from the Doc. The series later attempted to fix this by bringing Sarah back for a few episodes during Tennant's run, and giving her a spin-off series "The Sarah Jane Adventures", which took some of the sting of her less than ideal departure away.