Kerstin Gier (b. 1966) is the author of a number of German woman's titles.
Gier's first novel for young adults, Ruby Red, also titled as Girl About Time in one English edition, was published in the original German as "Rubinrot" (Ruby Red) and achieved instant success, selling over 100,000 copies in German alone. Kerstin has many loves, besides her love of writing including summer, strawberry cake, watching movies and playing piano. She lives in Germany with her husband, son and a very black cat.