Outlander · A Viewer's Companion
Outlander's cast isn't huge, but it's folded across two centuries: Claire is married in the 1940s and the 1740s, her 20th-century husband wears the same face as the 18th-century villain (one actor, two roles), and her daughter is born in 1948 to a father from 1721. The borders untangle it: tartan green for Clan Fraser, peat brown for the MacKenzies of Leoch, heather purple for the 20th-century line, and redcoat scarlet for the English — with a little spiral on everyone who has passed through the standing stones.
Six facts on this chart explain almost every "wait, who is that?" moment in seven seasons.
In 1945, on a second honeymoon with Frank, Claire touches a standing stone and wakes in 1743. To escape English custody she must marry a Scot — Jamie — while still, by her own reckoning, married to Frank two centuries away. The show never treats either marriage as fake: that tension powers everything.
One actor, Tobias Menzies, plays both the gentle 20th-century historian and the sadistic redcoat captain — because Frank descends from the Randall line and inherited the face. The cruel joke: Frank proudly researched "his ancestor" Black Jack, but the real ancestor is Black Jack's kind brother Alex. Jack married Alex's pregnant fiancée on the eve of Culloden so the child would carry his name. Frank's family tree is a polite lie.
Brianna was conceived in 1746 and born in Boston in 1948, raised by Frank as his own. Roger is the minister's adopted son from 1960s Inverness — and a direct descendant of Dougal and Geillis's secret child. Both inherit the ability to pass through the stones, follow Claire into the 1700s, and marry there. Their son Jemmy is born in colonial North Carolina.
The Leoch girl who pined for Jamie in Season 1 (and sent Claire to a witch trial) reappears in Season 3 as his wife — he married her believing Claire was gone forever. Claire's return ends it fast. But Laoghaire's daughter Marsali marries Jamie's adopted son Fergus — so Jamie ends up his ex-wife's co-father-in-law, forever.
While a paroled groom at Helwater, Jamie was coerced into one night by the bride Geneva Dunsany, who died giving birth. The boy, William, is raised an English earl by Lord John Grey — Jamie's friend — never knowing his groom "Mac" was his father. By Season 7 he's a redcoat officer whose mirror is telling him the truth.
Ellen MacKenzie, sister of laird Colum and war chief Dougal, scandalized the clan by eloping with Brian Fraser. That makes Jamie half MacKenzie — which is why his uncles at Castle Leoch alternately protect him and see him as a rival for little Hamish's inheritance. And Hamish himself is the clan's quietest secret: fathered by Dougal, raised as Colum's heir.
Between recycled names, aliases, and one actor playing two men, these are the pairs people mix up:
Same face, one actor (Tobias Menzies), 200 years apart. Frank: glasses, tweed, 1940s, kind. Black Jack: redcoat, riding crop, 1740s, monstrous. If Claire looks frightened, it's Jack; if she looks guilty, it's Frank.
Ian Murray — Jenny's steady, one-legged husband, Jamie's oldest friend. Young Ian — their restless son (John Bell), kidnapped to the New World in S3, later adopted by the Mohawk. Father and son, not the same man aging.
Same man. Born a MacKenzie (Dougal's line), orphaned in WWII, adopted by the Reverend Wakefield. When he goes to the past he takes his blood name back — which is why the 1700s keep calling him "MacKenzie" like half of Castle Leoch.
Both are James. Jamie = James Fraser. Jemmy = Jeremiah MacKenzie, Brianna and Roger's son, named for Roger's father. The nicknames are the only mercy.
One woman, three names: born Gillian in the 20th century, she went through the stones and became Geillis, the fiscal's poisoning wife in 1740s Cranesmuir — and resurfaces in S3 Jamaica as the widow Abernathy.
One arc, three phases: lovesick teen at Leoch → the note that sent Claire to the witch trial → Jamie's brief, bitter wife in the 1760s. Mother of Marsali (and Joan) by an earlier husband — not by Jamie.
The Paris brothel pickpocket Jamie renamed and raised. Loses his left hand to a redcoat blade as a boy — he and one-legged Ian Murray are the family's matched set of survivors.
On paper: the old Earl of Ellesmere (Geneva's husband). In practice: Lord John Grey, who raised him. In blood: Jamie — which is treasonous knowledge in a family of English officers.

Glenna FitzGibbons, head of Castle Leoch's kitchens and hearts — and, awkwardly, Laoghaire's grandmother.

Dougal's loyal man, half of the show's beloved comic duo — the stouter, kinder half. Meets the war's end at Culloden. †

The other half — wiry, filthy, devoted. Dies of wounds after Prestonpans in Season 2, and Rupert is never the same. †

Ardsmuir prisoner turned Ridge settler; Jamie's rigid religious rival — who quietly loves Claire.

Tom's unnerving daughter, Claire's apprentice — her false claim that her unborn child was Jamie's detonates Season 6, and her murder nearly hangs Claire. †
Portraits are stills from the Outlander wiki, cropped and self-hosted so the page loads with no third-party round-trips. Ellen MacKenzie never appears on screen in the main series; her portrait shows Harriet Slater, who plays her in the prequel Outlander: Blood of My Blood. Jemmy and Hamish are played by uncredited child actors. Chart and death-daggers reflect the story through the end of Season 7 — spoilers to there, none beyond.