S is for...

The SANCTUARY
Place set up by the Watchers for Immortals who wish to disappear completely from The Game. They're rigged up to machines and drugged, thus keeping them sedated. Unfortunately, some bright spark forgot to situate it on Holy Ground, with tragic consequences... ('Endgame')

SEACOUVER
An imaginary city in the north-west of the United States (set halfway between Seattle and Vancouver, hence the name) where Duncan spends a lot of his time.

May Ling SHIEN
The Immortal who taught Duncan the martial arts in 18th Century Mongolia. Yup, they took a tumble too (C12, 'They Also Serve').

SILAS
One of the original Four Horsemen of the Apocalypse who terrorised Bronze Age tribes, thus cementing their place in legend - see F (E11-12, 'Revelations 6:8' and 'Comes A Horseman').

Thomas 'SULLY' SULLIVAN
An old Irish friend of Duncan's whose love for boxing was tempered by his violent rages against people who went the wrong side of him. In 1896 he persuaded Duncan to fight for him in San Francisco; by 1993 he was pursuing the Highlander for help with his love life (B12, 'The Fighter').

T is for...

Richard TARSIS
Tarsis was a renowned thief in early 20th Century Europe who finally fell foul of Duncan's blade in 1930 Paris after killing one of the victims of his bank robbery, despite the Highlander's warning. He deliberately triggered the Immortality of his student Lucas Kagan by shooting him. As you do. (C20, 'Reasonable Doubt')