Doctor Who: 10 Things You Didn't Know About Captain Jack Harkness
9. He Has Roots In The Talons Of Weng-Chiang
Captain Jack Harkness is a Time Agent from the 51st century, which directly links him to the classic Tom Baker serial The Talons of Weng-Chiang.
The true villain of this serial is the brutal war criminal Magnus Greel, who was active during World War VI, which took place in the year 5000. After Greel was defeated, he escaped to Victorian London where he conducted his grisly experiments, living in fear of the Time Agency knocking on his door.
The Talons of Weng-Chiang is Doctor Who's first mention of Time Agents, a classic example of writer Robert Holmes' talent for building rich fictional worlds with just a few words. Then, when Russell T Davies brought the show back in 2005, he made the Time Agency a larger part of Doctor Who continuity.
Although Captain Jack was born a few decades after the defeat of Magnus Greel, he would follow in the footsteps of the very Time Agents that Greel had feared!
Torchwood Series 2 would later introduce another rogue Time Agent, Captain John, which really makes you wonder if the Time Agency does any sort of background checks before enlisting new recruits.