Don Eppes is a fictional character from the television series Numb3rs, portrayed by actor Rob Morrow. He is an FBI agent who leads a team investigating various criminal cases in Los Angeles. Don is known for his strong sense of justice and dedication to his work, often balancing the demands of his job with his personal life. In the series, Don's younger brother, Charlie Eppes, is a brilliant mathematician who helps him solve crimes using mathematical concepts. Their relationship is central to the show, highlighting the contrast between Don's practical law enforcement approach and Charlie's analytical thinking.