Alan Eppes is a fictional character on the television show Numb3rs, played by Judd Hirsch.

Alan Eppes is the amiable father of Charlie and Don Eppes, and is particularly protective of his younger son, Charlie. He is a widower and retired city planner, and in "Waste Not", Charlie referred to him as an engineer. He keeps busy by getting involved in the personal lives and careers of his sons as well as volunteering for causes he believes in. It makes him proud to see his competitive sons working together. Alan worries about his sons being able to settle down and have a family, especially given their problems in maintaining relationships with women for extended periods of time. Recently he had been on his first date since his wife's death, with a caterer he was fond of, and has once more taken up work, investing in a consulting firm with Stan Fisher, which is related to "all his years in urban infrastructure."

He is currently dating Dr. Mildred "Millie" Finch, Chair of the CalSci Physics, Mathematics, and Astronomy Division. When he is being sued by neighboring residents of a tennis court because of its disruptive lighting he designed, the relationship proves invaluable as Alan even overcomes the problem involving his new job venture with the aid of Millie, who helps Alan to discover that he is blameless. She also notes where Charlie gets his interest in numbers after overlooking Alan's engineering analysis of the lighting system ("End of Watch"). He later makes a bet with her whether they can go without consumer products.

For much of the first two seasons, his wife's name was never mentioned in the show, though she was referred to on the set as Margaret. He met Margaret when she was working for a tenants' rights organization and he was working for a housing developer. They had been married for thirty-five years and their marriage was a happy one, though they hid marital tension from their children. Alan held onto his wife's clothes, which he hid in the garage, despite Don helping him pack it six months before. When Charlie showed concern, he told him it was none of his business. Don confronted him as well, but both were criticized for giving advice as unmarried men and Mr. Eppes finally decided to get rid of the clothing on his own. After Charlie found a musical composition for the piano by his mother under her maiden name, Margaret Mann, in the Eppes garage, Alan revealed to his sons their mother's talent with classical music and her training in Vienna. He was astonished when his son noticed that some of her other compositions were dated after the birth of their children as he thought she had put her music work aside for her law career to help the family. Alan has seen his wife (JoBeth Williams) in a dream at the same time as Charlie.

Alan volunteered his son's house for Valerie Eng's (a girl Don and Charlie both liked during high school) wedding, toiled over coordinating every detail, and assigned the seating arrangement to Charlie, who created a mathematical algorithm for it, though Charlie didn't overall seem too enthusiastic about it. He claimed that since he never had a daughter, this would be his chance to make amends.

Alan has considered moving out of his son's house in order to live alone (something he has not done in forty years) and accomplish things on his own, but was rather hesitant to tell Charlie. He was shocked when his son seemed fine with it. Don tried to persuade him to take a place next to a tennis court, as his eldest son is fond of the game. Alan finally decided against moving, since he favors his sons' company over being alone. He wants a new staircase to his room. Moreover, he wants Charlie to be more responsible in maintaining the house and be able to have a family. After giving Charlie a hard time about his chores, he seemed to grasp Charlie's situation more fully after a comparison to Einstein's. More predicaments in his living arrangements are revealed when a break-in at his precious Craftsman home causes him grief ("Pandora's Box").

Like Don, he enjoys baseball. He has attempted to persuade Charlie to take up golf like him, delighted that he can at least teach his brilliant son something. He sometimes works on puzzles to occupy his time when not busy, continuing his wife's hobby and allowing time for conversing with Charlie's colleagues, Larry Fleinhardt and Amita Ramanujan, over pizza. He also enjoys an occasional game of chess with Larry and was surprised at his friend for his love interest in Megan Reeves and his nomadic lifestyle. Before he was with his wife he was often a "rail bird" at the horse races.

His recent involvement in his sons' lives has been extended to aiding the FBI more frequently with his expertise in urban planning ("Under Pressure") and traffic engineering ("Money for Nothing"). Don at first was adverse to his father getting involved with his line of work, but Alan asked him to show more respect.

Alan is auditing a mechanical engineering class at CalSci for fun, but Charlie is disappointed that he could not interest him in advanced mathematics after all these years ("Velocity"). Alan being on campus has Charlie note the similarity of the situation to that of Back to School. Being very busy, Charlie fails in helping to teach his father the engineering material, as all he does is solve the thermodynamic problem set from this class for him. Alan seems disappointed. Since then, Charlie has made notes to help him more later, and feels that this will make up for all the times missed with his father getting to help him with homework. On the other hand, Alan recalls all the dioramas he created with him.