Short answers, pulled from the story.
Adam Driver portrays Kylo Ren in all three sequel trilogy films: The Force Awakens (2015), The Last Jedi (2017), and The Rise of Skywalker (2019). He also voices or provides motion for the character in various related media.
Kylo Ren's birth name is Ben Solo. He is the son of Han Solo and Leia Organa, and the grandson of Darth Vader.
Kylo Ren was trained as a Jedi by his uncle, Luke Skywalker. He was seduced to the dark side of the Force by Snoke, the Supreme Leader of the First Order, and took the name Kylo Ren while aspiring to match his grandfather, Darth Vader.
Adam Driver won the Saturn Award for Best Supporting Actor for his performance as Kylo Ren in The Force Awakens, making him the first Star Wars actor since Alec Guinness to win the award. He received a second nomination in the same category for his performance in The Rise of Skywalker.
Kylo Ren and Rey share a connection called a Force dyad, revealed in The Rise of Skywalker. Screenwriter Chris Terrio described the pair as "sort of soulmates in the Force" and "twins of fate, twins of destiny."
Kylo Ren dies in The Rise of Skywalker after using the last of his life force to revive Rey when she collapses following her fight with the resurrected Emperor Palpatine on Exegol. He shares a kiss with Rey before dying, and his body fades into the Force alongside Leia's.