04/21/2004 at 01:00 AM EDT
Christian Slater and his girlfriend, TV executive Ryan Haddon, have had a baby boy, Christian's mother, Mary Jo Slater, has told PEOPLE Magazine's "Insider" columnist Nancy Perry Graham. The baby, Jaden Zach Haddon-Slater, arrived Tuesday at Manhattan's Lenox Hill Hospital. "Mother and baby are doing great," first-time grandmother Mary Jo, who is a casting director and producer, told Graham. (Christian's father is Michael Gainsborough, a stage and soap actor.) Slater, 29, and Haddon, 28, have been dating for the past year. He recently finished a stint on Broadway in the drama "Side Man" (about journeymen musicians), for which he earned excellent reviews. Young Jaden, his grandmother reports, is a handsome lad: "The baby looks just like Christian."