The absolute, only situation in which it could be conceivably ethical is one like the following, in Exodus 1:15-21:
The king of Egypt said to the Hebrew midwives, whose names were Shiphrah and Puah, "When you help the Hebrew women in childbirth and observe them on the delivery stool, if it is a boy, kill him; but if it is a girl, let her live." The midwives, however, feared God and did not do what the king of Egypt had told them to do; they let the boys live. Then the king of Egypt summoned the midwives and asked them, "Why have you done this? Why have you let the boys live?"
The midwives answered Pharaoh, "Hebrew women are not like Egyptian women; they are vigorous and give birth before the midwives arrive."
So God was kind to the midwives and the people increased and became even more numerous. And because the midwives feared God, he gave them families of their own.
Another example of this is in WWII, the Ten Booms, a Christian family, made a secret compartment for Jews in their home, as part of a stop on an "underground railroad" to save them from the death camps. You can read about that in "The Hiding Place," a true story by one of the daughters, who went on to speak in many churches internationally after the war, telling her story.
Short of that, you do not lie. Period.