Ben was born in New York circa 2006.
He may have been named after Will's old boss Ben Doucette (whose portrayer Gregory Hines died in 2003) or because his portrayer Ben Newmark has the same name. It is never stated what is Ben's last name, though it may have been Truman-D'Angelo. He gets engaged to Grace and Leo's daughter Lila.
Will jokes that Ben's biological mother "sold her eggs for rent money", implying he was conceived via in vitro fertilization. Vince hints that Will may be his biological father.
In the first episode of the revival series, Karen wakes up from a drug-induced dream and asks "What happened to the kids you had that grew up and married each other?" Will looks confused and confirms he and Grace have no children.