Endovorm

The stone lions were used by the Sevakrill to guard Nelson's Column while they prepared a missile inside it. As the name suggests, they had the appearance of lions.

The lions were made invisible by perception filters to anyone from that time. While the Fifth Doctor climbed the column, the lions tried to kill Tegan Jovanka and Nyssa. They killed seven civilians and a policeman before the Sevakrill were cast out. They then returned to their plinths and when their filters ran out after a few decades, Edwin Landseer unveiled them as his own creation. The Metropolitan Police Service wrote off the deaths as the result of a bus crash. (ST: The Lions of Trafalgar)