Yes, in the Twilight series, there is a human-vampire hybrid named Renesmee Cullen. Renesmee is the daughter of Edward Cullen and Bella Swan. Her birth and existence are central to the plot of the fourth book, "Breaking Dawn."
Renesmee is a unique and rare being as she is half-human and half-vampire. She is conceived while Bella is still human, and her rapid growth in the womb presents significant dangers to Bella's life during her pregnancy.
After Bella becomes a vampire and gives birth to Renesmee, it becomes clear that she possesses a blend of human and vampire qualities. She has the appearance of a beautiful, half-vampire child, but she also exhibits some human traits, such as a beating heart and the ability to grow and age at a faster rate than normal vampires.
Renesmee's presence leads to conflicts and misunderstandings with the Volturi, who initially view her as a potential threat to the secrecy of the vampire world. However, over time, it is revealed that Renesmee has a unique ability to communicate her thoughts and experiences through touch, which proves beneficial in dispelling any misunderstandings.
Renesmee's existence plays a significant role in shaping the events of "Breaking Dawn," bringing her parents, the Cullen family, and their allies into a confrontation with the Volturi. Her character adds an element of uniqueness to the series and explores themes of family, acceptance, and the possibilities of hybrid life in the Twilight universe.