Albert Simpson, an Annenberg Hall dishwasher who served behind-the-scenes in Harvard dining halls for 13 years, died at his home in the Cambridge area on Sept. 29. He was 79.

The cause of death is unknown, said Judy Della Barba, director of human resources at Harvard University Dining Services (HUDS).

"He was a dear gentleman, very quiet and wonderful," said Annenberg General Manager Katherine D'Andria.

Simpson first joined HUDS in 1989, working in the Faculty Club before transferring to Annenberg when it was renovated into a first-year dining hall.

"He had this beautiful-weather disposition, and was extremely energetic," said Jordan A. A. Bar Am '04, who worked alongside Simpson one day each week in 2000. "He, in his late 70s, did work that would even make me exhausted."

According to D'Andria, Simpson was so unfailing in coming to work that, when his coworkers noticed his absence last Monday, she knew immediately that "something was wrong."

So she called Simpson's home, where he lived by himself, and got no answer. Later she got in touch with a friend of his, who told her Simpson had died the day before.

"It was so unexpected," she said. "I just saw him at work on Friday, and he looked fine."

Simpson was known among his fellow workers from Central America and Portugal as "Alberto."

"He was so wonderful and so nice, someone who always had a smile," said Mary Correia, one of his Annenberg coworkers.

Simpson lived alone and, except for a nephew and a close female friend, has no known survivors. A service has been tentatively planned for next week.