Issabella María Concepción is a Cuban maintenance worker at the Caltech whom Rajesh Koothrappali dated. She has a nineteen-year-old son and was once married. Raj really likes her and fixed her dinner in the Telescope Lab.
In "The Brain Bowl Incubation", Raj is in the telescope lab looking for extraterrestrial planets when Issabella the maintenance worker comes in. Raj possibly finds an extra-solar planets that could have life on it and could be named after him. Issabella wonders if there is life, maybe it already has a name. Raj helps her with the trash and they do stare at each other for a moment and say goodbye. Later, while eating dinner in Apartment 4A Penny guesses that he is interested in someone since he is eating l0-cal steamed broccoli. Since he met her in the telescope lab Leonard figures that she is an astronomer and then Raj doesn't correct him.
While Raj is helping Issabella clean the men's room, he also mentions that he had a cleaning lady and other servants when he was growing up. Raj finds out that she is unmarried and has a 19-year-old son in law school at UCLA. She appreciates the interest, but she works two jobs and has no time for dating. She tells him "Good night", though Raj while leaving says that he still thinks that there is something going on between them.
Another night Issabella comes into the telescope room to work and has found that Raj has made them dinner since she was too busy to go out. He even cleaned up the next offices so that she could take a break. He made what he claimed was food from her homeland; however she is Cuban and not Mexican. They talk about when they first came to America. She mentions that she has some time off on Sunday as Howard comes in. He asks if she was the astronomer that Raj met. Issabella is not happy and leaves because she is not going to waste her time with someone who is embarrassed by her. Raj runs after her to apologize and he tells her embarrassing things about him. Finally she says that he can take her out to a nice place to eat on Sunday night and it can be Pakistani food if he likes. He says he's Indian, to which Issabella says now he knows what it's like to be stereotyped.
In "The Emotion Detection Automation", it is revealed that Issabella broke up with Raj. No reason or explanation is given.
- It's unknown what became of Issabella's husband as she was not wearing a ring under her gloves, and hadn't worn one for years. This suggests that either Issabella is a widow or divorced.
- She is played by Maria Canals-Barrera who is best known for Voicing Hawkgirl in Justice League and Justice League Unlimited, Paulina in Danny Phantom, and Theresa Russo in Wizards of Waverly