As an English name, Aaron has been in use since the Protestant Reformation. This name was borne by the American politician Aaron Burr (1756-1836), notable for killing Alexander Hamilton in a duel.
There was a medieval English form of this name, Helewis, though it died out after the 13th century. In the 19th century it was revived in the English-speaking world in the form Eloise.
In the United States this form was much less common than Isabel until the early 1990s, when it began rapidly rising in popularity. It reached a peak in 2009 and 2010, when it was the most popular name for girls in America, an astounding rise over only 20 years.
A famous bearer is the Italian actress Isabella Rossellini (1952-).
It has occasionally been used as an English given name since the 16th century. It was moderately popular in the 1940s, but had a more notable upswing in the early 2000s. This may have been inspired by the Spanish actress Penélope Cruz (1974-), who gained prominence in English-language movies at that time. It was already rapidly rising when celebrities Kourtney Kardashian and Scott Disick gave it to their baby daughter in 2012.
The name was common among Jews in the Middle Ages, but it was not generally used as a Christian name in the English-speaking world until after the Protestant Reformation. It was moderately popular in the first half of the 20th century, but starting in the 1960s it steadily rose, reaching highs in the 1980s and 90s. The character Rachel Green on the American sitcom Friends (1994-2004) may have only helped delay its downswing.
Notable bearers include American conservationist Rachel Carson (1907-1964), British actress Rachel Weisz (1970-), and Canadian actress Rachel McAdams (1978-).