Marshal of the Indian Air Force Arjan Singh is the only officer of the Indian Air Force to be promoted to five-star rank, equal to a Field Marshal, to which he was promoted in 2002.
With the death of Field Marshal Sam Manekshaw in June 2008, he is the only living Indian military officer with a five-star rank.
Singh almost faced a court-martial in February 1945 when he tried to raise the morale of an trainee pilot ( later rumoured to be future Air Chief Marshal Dilbagh Singh) by conducting a low level air pass over a house in Kerala, but he insisted that such tricks are needed for every cadet to be a fighter pilot.
Indian military officers of five-star rank hold their rank for life, and are considered to be serving officers until their deaths.
text and image source: https://en.wikipedia.org/wiki/Arjan_Singh