Bancroft was a senior member of the Watchers
organisation who was killed by fellow Watcher Rita Luce when he
suspected that her relationship with her charge, Immortal Michael
Christian, wasn't purely observational. Bancroft had been watching
May-Ling Shien, an old flame of Duncan's (who wasn't?), but she was
killed by Christian after a tip-off from Luce (C12,
They Also Serve).
Duncan Macleod, Hugh Fitzcairn and Xavier St Cloud cannot be killed
unless they are beheaded. The Immortal can be 'killed' temporarily,
but will revive and heal. Any wounds (aside from amputations) and scars are also healed, and
they are immune to disease. Being sterile, Immortals have little need
for birth control and so tend to put themselves about a bit. Well,
Duncan does (and Fitz come to think of it) anyway.
Macleod was shipwrecked here in 1778. His rescuer,
Hideo Koto, was forced to commit hara-kiri as a result of harbouring
an outsider in the isolationist empire. Still, Duncan did get his
katana out of it, and has carried Koto's sword as his own ever since (C1,
Ex-lover of Amanda's, who calls on her and Nick for
help when he becomes convinced his son was killed by the government
for trying to expose a conspiracy involving attempting to manipulate
the world's population levels (more's the pity) -
R5, 'So Shall Ye Reap'.