E is for...

The EXECUTIONER
Better known as Kalas (C14, 'Song of the Executioner'). The Immortal equivalent of the Singing Nun had few friends in the monastery he was living in the 17th Century, mainly because he beheaded them all whenever they left the sanctuary of Holy Ground (see H). Lost his voice to Duncan's sword some 70-odd years before finally relinquishing his head to the Highlander atop the Eiffel Tower (C22, 'Finale part two'). Not a nice chappie.

ERNST Daimler
Ernst had two things going against him. First, he was a Nazi officer in World War II. Second, he spent nearly 50 years buried in the River Seine. Must have been numbing - for the body and mind. (C19, 'Mortal Sins').

F is for...

FELICIA Martins
This French Immortal was the first female baddie we got to see in the series. She bore a passing resemblance to rock star Joan Jett (even shared her East Coast accent), and was the first Immortal to survive a battle with our Dunc, due to his misguided sense of chivalry. He soon gained the ability to lop off female heads - just ask Nefertiri (see N), so Felicia has sensibly kept her distance since (A5, 'Free Fall').

FITZ (Hugh FITZCAIRN)
Of 12th Century English vintage, the foppish Fitz was one of Duncan's best friends (this is unsurprising, considering their shared passion for wine, women and song). Despite dying at the hands of Kalas (C15, 'Star-Crossed'), we've since been treated to other excerpts in Fitz's life, from 1750 to 1950, via 1929 and other eras. He even appeared as an 'angel' to Duncan in the series finale (F12, 'To Be'; F13, 'Not to Be').

FLASHBACK
You're often treated to flashes from Duncan's past, usually involving other Immortals and, you've guessed it, beautiful women. No wonder Connor is jealous.

FOUNDLING
No one actually knows where Immortals come from. No Immortal knows his natural parents because to a man (and woman) they've all been found as babies, then adopted. This has led to the term 'foundling' being used in association with Immortals. It's rumoured the next Highlander movie, currently called The Source, may go some way to answering this question.

FOUR HORSEMEN
Four Immortals, Methos, Kronos, Caspian and Silas, terrorised mankind for centuries from the Bronze Age on. They returned in 1996 with a predictable 'destroy the world with a deadly virus' gag (E11, 'Comes a Horseman'; E12, 'Revelations 6:8').