Swedish number one Larsson was beaten 6-4 6-1 by Williams in the final of the WTA clay-court event last year, but the world number one will not be in Bastad next week as she continues to recover from illness.
American Williams had to retire from her second round doubles match at Wimbledon due to a viral illness and is still not well enough to return to the court.
World number 73 Larsson gave a great account of herself 12 months and will aim for another long run in this year's tournament.
Flavia Pennetta is also unable to feature in Bastad due to an ankle injury sustained in her first round match at the Nurnberger Gastein Ladies this week.
Spaniard Carla Suarez Navarro is another absentee after she was forced to pull out of the same tournament with a back problem that was troubling her during a second-round match against Shelby Rogers.
Swedish teenager Rebecca Peterson has been given a wildcard into the tournament and the 18-year-old is relishing the opportunity to take her place in the main draw for a third time.
She said: "The first year I was very nervous. I did not know what was waiting on the Centre Court, you do not want to make a fool of yourself and you are afraid that it will end in a disaster.
"The second time you have more experience and feel that you have the advantage of playing in a familiar environment.
"And now? I think I'm even more ready. I believe even more in myself, it's something that you build up and develop year after year."
Italian Camila Giorgi and Yvonne Meusburger of Austria are among the other players who will be looking to make the most of Williams' absence by claiming the title.