Amanda Grayson was a Human teacher from Earth born around the turn of the 23rd century. During the early 2230s, Amanda met Sarek, the Vulcan Ambassador to Earth. The two later married, and she returned to Vulcan with Sarek. In later years, in describing his parent's relationship, Spock stated that his mother "considered herself a very fortunate Earth woman."

In 2232, Amanda gave birth to her only son, Spock.

It was not uncommon for Spock to mention his mother's origins. While under the influence of the polywater intoxication, Spock regretted that he "could never tell her that he loved her." Spock once spoke of Amanda's fondness of reading the works of Lewis Carroll. She often read stories, such as Through the Looking-Glass, to Spock during his youth.

In an alternate timeline created by the death of Spock in 2239, Amanda and Sarek separated and she returned to Earth, where in transit, she was killed in a shuttle accident at Lunaport.

During the Babel Conference of 2268, she accompanied her husband aboard the USS Enterprise, and helped Sarek and Spock to reconcile some of their differences. Spock wondered why his father would marry an emotional woman; Sarek replied it seemed the logical thing to do at the time, a comment that Amanda found quite charming.

During this journey, Captain Kirk was at a loss on how to properly refer to her, calling her "Mrs. Sarek." Amanda said that her married name was usually unpronounceable by Humans, although she could do it, "after a fashion, and with much practice." She said to simply call her "Amanda." In the Vulcan society, she was referred to as "the Lady Amanda."

In 2286, Amanda helped her son to re-educate himself, after his death and rebirth on the Genesis Planet and fal-tor-pan rejoining. In particular, she tried to help Spock rediscover his Human side. see Star Trek IV: The Voyage Home

Years after her death, Sarek hadn't forgotten her. During his Bendii Syndrome, he regretted not having been tender to her, and having never told her how much he loved her.