Often refers to a performer of traditional Japanese arts such as Noh, Kabuki, or classical music, but can also be used more broadly for entertainers.
He is known as a performer of traditional performing arts.
芸能人 is the standard modern term for a celebrity or entertainer in show business, whereas 芸能者 is less common and can sound more traditional or formal.
Compound of 芸能 (performing arts) and 者 (person). The exact historical derivation is uncertain, but the word follows a standard pattern for forming agent nouns.