several space flight records.
No other woman has spent so much uninterrupted time in space, no other woman has worked on four spacewalks and no woman has spent so much time working in free space - 29 hours and 17 minutes.
Suni, as she likes to be called, is returning home aboard the Space Shuttle Atlantis, which is to land at NASA's Kennedy Space Centre in Florida on Thursday. On Sunday, she surpassed the female record set in 1996 of 188 days in space.
The NASA control centre has done its best to keep Williams happy during her time in space.
After months of space cuisine, the food was getting bland. In her NASA diary, Williams praised efforts to mix it up with sushi, curry vegetables, chicken with peanut sauce and a breakfast of warm, spiced apples, ham and an omelette.
Salmon with wasabi sauce and ginger especially excited her. "They were the fine makings of a meal!" she wrote in her online NASA journal.
Unfortunately, as she opened the lid just a millimetre, out rushed the sauce "like a fire hose". It flew across the room, floating until it hit the walls.
Williams is married and has no children. Born on September 19, 1965 to an Indian immigrant and an American mother, Williams grew up celebrating both Indian and American holidays, listening to Indian spiritual leaders but also attending Roman Catholic religion classes at her mother's church.
"I think it made (Williams and her siblings) very open-minded about different people," Williams' mother Bonnie Pandya said in a telephone interview shortly after Williams left for space.
The astronaut can also call herself Miss Fitness. On firm ground she windsurfs, snowboards and competes in triathlons. She didn't let being more than 300 km above Earth slow her down - instead she ran a marathon.
The first person to complete one of the 42-km races from space, she ran the famed Boston Marathon in four hours 23 minutes.
"She truly is a space marathoner who shows young women everywhere that there's a place in the space programme for them," fellow astronaut Eileen Collins was quoted by NASA as saying of Williams' accomplishments.
During her time in space, Williams also donated to charity by cutting off her ponytail for the group Locks of Love. Her hair will be used to make wigs for children who have lost their hair during chemotherapy.
Fellow American Clayton Anderson, who is to stay on ISS until October, is replacing Williams.