In Oedipus of Sophocles, Iokaste advised her son and husband not to

"There is no meaning in life."

In Oedipus of Sophocles,
Iokaste advised her son and husband not to believe in Delphi trusts and prophecies, saying, "Humans are governed by chance and can't see anything for sure, so what good is it that they are afraid? It is best to live as much as possible from day to day. So don't be afraid of marrying your mother. Many men have already slept with her in their dreams, as they did in the oracle. You should grow up to think nothing of it, so you can live your life at its most comfortable." (King Oedipus, 977-983)

Lulu Miller's "Fish Does Not Exist" also features a character with a similar worldview. He is the father of the writer.
When Miller asked what the meaning of life was, his father's answer was.

"There is no meaning. There is no god. There is no godly being to watch or care for you in any way. There is no afterlife, no destiny, no plan. And don't trust anyone who says there is. All that stuff is just imagined by people to appease themselves against the terrifying feeling that all this means nothing and they don't mean anything. The truth is all this, and neither do you."

Lulu Miller's "Fish Does Not Exist", 51.