One popular theory comes from a story in the Quran, the holy book of Islam, about Ibrahim and his son, Ismail.

In Islam, Ibrahim is known as the father of the prophets, and upset that people in his hometown still worshiped idols and not Allah, he smashed all but one statue in a local temple with an ax. Ibrahim's son is Ismail, who also became a prophet. Ibrahim is Arabic for Abraham, who plays a big role in Christianity, Judaism and Islam.

In two classic American books, Ismail is spelled Ishmael.

In James Fenimore Cooper's novel "The Prairie," Ishmael Bush is an outlawed warrior, according to an essay written in 1969 by William H. Goetzmann, a University of Texas history professor. In Cooper's book, "Bush carries the prime symbol of evil — the spoiler's axe," he wrote.