Ramona Nowitzki, Ph.D. (Riki Lindhome) first appears in the season 2 episode "The Cooper–Nowitzki Theorem", when she is a graduate student at Caltech. She is a huge fan of Sheldon's work and develops a crush on him. She blew him off after Sheldon refused to share credit with her on a theorem he developed. She later reemerged in the Season 10 finale where she kissed him, only for him to further pursue Amy and propose to her.