The strong and intelligent older sister of Jean Grey and daughter of Dr. John & Elaine Grey, Sara was a firm believer in the mutant cause. Though not a mutant herself, she supported her sister and the X-Men with all her heart, and was often ridiculed by others for it. When Jean left for the Xavier Institute, Sara made a promise with her that if Jean would use her powers to help save people, Sara would love her no matter what had happened. While she supported mutants, she often worried what would happen if her own children, Joey and Gailyn to her husband Paul Bailey, became mutants. After Jean's death, Sara often visited her grave, and remembered the times they had. One such adventure took place in Atlantis, where Attuma kidnapped the two sisters and planned on marrying them. They escaped, and as Sara came back to her senses, her apprehension over her children vanished and she knew if her children were anything like Jean was, she'd be very proud.

After Jean's resurrection, Sara went missing. While most of the X-Men thought it was mutant-hating groups, it was really the Phalanx that had absorbed her into its system. She was later found by Banshee, but it was too late to save her. Her death was mourned by Jean Grey and her family for years. Her children were eventually killed by the Shi'ar Death Commandos who wished to prevent any resurgence of the universe-threatening entity known as the Phoenix. It is unknown what happened to her husband, Paul Bailey.

Sara Grey appears in the X-Men animated series in "The Dark Phoenix Saga (Part 3): The Dark Phoenix" near the end of the episode and in the first few minutes of "The Dark Phoenix Saga (Part 4): The Fate of the Phoenix". She is seen in both episodes with her father, Dr. John Grey, and mother, Elaine Grey, as they worry over the state of Jean Grey who is possessed by the Phoenix Force. In the former episode she and her parents are being protected by Gambit and Professor X as the other X-Men battle the Dark Phoenix and in the latter they watch helplessly as a reformed Jean and the X-Men are transported by the Shi'ar to outer space. Neither she or her parents have any lines in the episodes.

Sara Grey appeared in a few episodes of X-Men: Evolution, notably the episode On Angel's Wings, in which Jean goes home with her family over Christmas. Jean, along with Sara and both of their parents, are seen buying so-called Christmas Trees. Sara did not have a speaking role in any episode of the series.