Part of The Brat Pack featuring Emilio Estevez, Rob Lowe, Molly Ringwald, Anthony Michael Hall, and Ally Sheedy.
John Bender wasn't a character Nelson played, it was a character he became. He stayed in-role so aggressively on set that John Hughes tried to fire him midway through production, and it took the entire cast staging an intervention to keep him on. The method acting paid off: The Breakfast Club (1985) and St. Elmo's Fire (1985) made him the rebel face of the Brat Pack. The role that almost got him fired is the one he's been defined by ever since.
The Brat Pack moment faded faster than anyone in it expected, but Nelson kept working. He earned a Golden Globe nomination for Best Actor for Billionaire Boys Club (1987), a turn that should have relaunched his career but mostly didn't. A recurring role in Empire brought him back to mainstream television in 2015, and he's picked up guest spots and direct-to-video work ever since. He never disappeared entirely, he just stopped being the guy everyone was watching.
His father was a corporate attorney who became the first Jewish president of the Portland Symphony Orchestra; his mother served in the Maine House of Representatives. He trained at the Stella Adler Conservatory, studied hard, and then spent most of his career playing a guy who hated all of that. He's never married, keeps no social media presence, and gives almost no interviews. The face of 1980s delinquency was raised by overachievers.