X-Files star Gillian Anderson and boyfriend Mark Griffiths are parents of a baby boy, the actress's rep tells PEOPLE exclusively.

Felix Griffiths, weighing 6 lbs., 15 oz., was born Oct. 15 in London, says rep Kelly Bush.

Felix is the second child for Anderson, 40, with Griffiths, joining their 1-year-old son Oscar. Anderson also has a 14-year-old daughter, Piper, from a previous marriage.