Here is a comprehensive summary of the Wikipedia article about the name Evan:
Evan is a Welsh masculine name derived from Iefan, a form of John, ultimately stemming from the ancient Hebrew name Yəhôḥānān, meaning "Yahweh is gracious." It can also be a shortened form of Greek names like Evangelos, and notably, it's occasionally given to women, as seen with actress Evan Rachel Wood, despite similar-sounding names like Owen having different etymological roots.
In the United States, Evan's popularity for males surged from 440th in 1957 to a peak of 35th in 2009 before experiencing a significant decline, falling out of the top 100 by 2020. In stark contrast, its use as a female name, which also began rising in the late 1970s, more than tripled as a share of overall use during the same post-2009 period when male usage dropped. By 2021, the name had modestly increased in popularity above its 2010 usage among American girls, showcasing a notable shift in gender usage trends.