US authors George RR Martin and John Grisham are suing ChatGPT-owner OpenAI over claims their copyright was infringed to train the system.
Martin is known for his fantasy series A Song of Ice and Fire, which was adapted into HBO show Game of Thrones.
ChatGPT and other large language models (LLMs) "learn" by analysing a massive amount of data often sourced online.
The lawsuit claims the authors' books were used without their permission to make ChatGPT smarter.
OpenAI said it respected the rights of authors, and believed "they should benefit from AI technology".
Other prominent authors named in the complaint include Jonathan Franzen, Jodi Picoult and George Saunders.
The case has been brought to the federal court in Manhattan, New York, by the Authors Guild, a trade group in the US working on behalf of the named authors.
According to the filing, it accused OpenAI of engaging in "systematic theft on a mass scale".
It follows similar legal action brought by comedian Sarah Silverman in July, as well as an open letter signed by authors Margaret Atwood and Philip Pullman that same month calling for AI companies to compensate them for using their work.
A spokesperson for OpenAI said: "We're having productive conversations with many creators around the world, including the Authors Guild, and have been working co-operatively to understand and discuss their concerns about AI.
"We're optimistic we will continue to find mutually beneficial ways to work together."