Skarloey is the sage of the Skarloey Railway and is an old, faithful little engine. Although once full of enthusiasm and his own ideas in his youth, Skarloey is now one of the oldest engines on the Island. He is a calm-natured, quaint, and mature engine and may often try to guide or watch over less experienced narrow gauge engines in his firm but fair and friendly manner. He acts kindly to engines and passengers alike and always enjoys a gentle, smooth journey through the woods by the lakeside and stopping at all the gates and stiles he remembers so well.
Skarloey is based on the Talyllyn Railway's Talyllyn, a Fletcher, Jennings Class C 0-4-2ST. In the Railway Series, Talyllyn is Skarloey's twin. The Ghost Engine shares the same basis.
In the Railway Series, Skarloey is painted in the Skarloey Railway's standard red livery with blue-and-yellow lining and with his name painted in gold on his saddletank, and a brass dome. In the television series, Skarloey was painted red with white lining. From Season 9 onwards, he is painted crimson red with white and gold lining. He has red and gold name and numberplates on the sides of his saddletank and cab respectively.
- Season 100 - Henry the Warrior (cameo), Samson's Waste Dump (cameo), Coach Brakes (cameo), Scottish Engines, Rheneas' Risky Ride, Duncan's Dilemma, Sidney Helps Out, and Rusty Rescue
- Keith Wickham (UK/US; sixteenth season onwards)
- Tomohisa Asō (Japan; fourth - seventh seasons)
- Hideyuki Umezu (Japan; ninth season onwards)
- Jens Wendland (Germany)
- Jacek Król (Poland)
- Gilan Shachaf (Israel; King of the Railway)
- Sigbjørn Solheim (Norway; sixteenth and seventeenth season, excluding King of the Railway)
- Simen Sand (Norway; Blue Mountain Mystery onwards, excluding the sixteenth and seventeenth season)
- Bruno Marçal (Brazil)
- Esteban Desco (Latin America; Blue Mountain Mystery onwards)
- Jorge Teixeira (Spain)
- Jukka Voutilaninen (Finland; Blue Mountain Mystery onwards)
- Keith Wickham gives Skarloey a Welsh accent.
- Skarloey was built at Fletcher, Jennings, and Co. at Whitehaven, the same place as Rheneas, Captain Baxter, Talyllyn and Dolgoch.
- His name means Lake in the Woods in Sudric.
- Skarloey's name on the Japanese Thomas website is backwards.
- In the Polish narration, Skarloey's name is Sławek, which is also Stephen's name in the same narration.
- Skarloey's large scale model was used as The Ghost Engine in Duncan Gets Spooked.
- The Reverend W. Awdry's model of Skarloey is currently on display at the Narrow Gauge Museum in Tywyn.
- Nitrogen Studios went to the Talyllyn Railway and took measurements of Skarloey's basis; Talyllyn and other locomotives No.2, No.3, No.4 and No.5 so they could make Skarloey's CGI model for the Skarloey Railway engines return, in the sixteenth season.
- Skarloey has gone through many modifications through the TV Series. These include:
- Season 5:
- Cab handrails disappeared (large scale model only).
- His buffers changed from grey to silver.
- Season 6:
- The brass ring around his funnel and his buffers were painted black.
- His model is significantly less weathered.
- Season 9:
- A tail lamp was added.
- His red livery became a dark crimson colour.
- Season 16:
- Accurate bufferbeam to his basis.
- His boiler is painted black instead of red.
- Handrails across the top of his smokebox and saddle tank like his basis.
- His cab handrails returned, but now gold instead of red.
- His cutout windows gained brass frames and contained glass.
- His tail lamp changed to a removable Talyllyn-styled lamp.
- Sanding gear.
- Black siderod guards.
- Extra lining on his cab.
- Footsteps underneath his cab.
- A rear numberplate similar to his basis and one illustration in Mountain Engines.
- Season 100:
- His handrails were painted silver.
- His side rods become silver.
- His cab handrails became silver.
- The text on his nameplates are now gold.
- Season 5: