Howard Wilson "Bill" Tindall, Jr. (February 20, 1925 – November 20, 1995) was an American aerospace engineer, NASA engineer and manager. He was an early expert in orbital mechanics and coordinated mission techniques during the Apollo program. In the words of flight director Gene Kranz, Tindall "was pretty much the architect for all of the techniques that we used to go down to the surface of the Moon." Tindall was known for the colloquial and entertaining tone of his memos, which were widely referred to as "Tindallgrams." One memo was simply titled "Vent bent descent, lament."