Zelda Williams, 25, an actress who is one of the comedian's three children, posted the words "thank you" on Twitter on Monday and linked it to a quote from actor and playwright Harvey Fierstein that appeared to take aim at online bullying.
"Never be bullied into silence," the quote said. "Never allow yourself to be made a victim. Accept no one's definition of your life; define yourself."
Zelda Williams announced she was going to quit using Twitter on Aug. 12, the day after her father's body was discovered at his San Francisco Bay-area house.
She made the decision after at least two Twitter users sent to her Twitter account graphic photos that were visually manipulated to look like pictures of a dead Robin Williams, according to media reports at the time.
Zelda Williams had also complained of negative online comments from some other Web users. "Deleting this (Twitter application) from my devices for a good long time, maybe forever," she wrote on Twitter on Aug. 12.
A number of Web users posted messages to support for Zelda Williams after her father's death and after she quit the site.
Robin Williams, who won an Oscar for his role in the 1997 drama "Good Will Hunting," was one of the world's most well known stand-up comedians. In one of his most recent roles, he starred in the CBS show "The Crazy Ones."