How Old Mulder Was At The Beginning & End
FBI special agent Fox Mulder's official birth date is October 13, 1961. This actually makes him ever so slightly younger than actor David Duchovny, who was born on August 7, 1960. While The X-Files' pilot episode aired in September 1993, it was shot in March 1993, and that's where the accepted series timeline places it. That means Mulder was a fresh-faced 31 when he first met Scully and they worked their first case together. The season 11 finale, "My Struggle IV," is generally accepted to take place around when it aired on March 21, 2018. That would put Mulder at 56-years-old.
How Old Scully Was At The Beginning & End
FBI special agent Dana Scully's official birth date is February 23, 1964. That actually makes her considerably older than actress Gillian Anderson, who was born on August 9, 1968. While that might seem weird, it's well-known that Anderson exaggerated her age to get the part, which is the opposite route most actresses take. As for Scully though, that puts her at a mere 29-years-old when she walked into the office of the FBI's most unwanted and began a journey that would define her entire life. By the end of season 11, Scully would then be 54-years-old.
This leads to a conclusion: if The X-Files season 12 ever happens, they're probably going to be rapidly nearing retirement age.
Via Screen Rant