Rheneas has been called a "gallant old engine" before and deserves such a title. Rheneas is highly determined, brave, courageous, and a long-time friend and brother of Skarloey. He is a tough, committed worker despite his age and takes great responsibility in his work. He is keen to keep his friends smiling and, although he is a level-headed engine, he can be a bit of an adventurer too. Though he may often try to struggle on alone, Rheneas knows when it is time to call on the help of his friends. Nevertheless, Rheneas is always highly dedicated to the task at hand.
Rheneas is based on the Talyllyn Railway's Dolgoch, a Fletcher Jennings Class Bb 0-4-0WT. In the Railway Series, Dolgoch is Rheneas' twin. Smudger and the Red Mid Sodor Engine]] are other members of this class.
In the Railway Series Rheneas is painted in the Skarloey Railway's red livery with blue and yellow lining, with his name on his boiler in yellow.
In the television series, Rheneas is painted vermilion with black lining and brass fittings. He has black and brass name and number plates on the sides of his boiler and coal bunkers respectively. In early magazine illustrations, he was painted carmine. This carried over to nearly all his merchandise. In Blue Mountain Mystery, he was repainted yellow with blue lining to play a joke on Thomas. He was painted back into his original livery soon afterwards.
- Season 100 - Henry the Warrior, Trouble with Brakevans (cameo), Samson's Waste Dump (cameo), Coach Brakes, Scottish Engines, Rheneas' Risky Ride, Duncan's Dilemma, Sidney Helps Out (cameo), and Rusty Rescue
- Ben Small (UK/US; sixteenth season - eighteenth season)
- John Hasler (UK/US; twentieth season onwards)
- Ryōtarō Okiayu (Japan; fourth - seventh seasons)
- Daiki Nakamura (Japan; ninth season onwards)
- Jesse Grimm (Germany)
- Gadi Levy (Israel; King of the Railway)
- Stan Limburg (The Netherlands)
- Anders Sundstedt (Norway; sixteenth season only)
- Sigbjørn Solheim (Norway; seventeenth season only)
- Stig Krogstad (Norway; Blue Mountain Mystery onwards, excluding the seventeenth season)
- Noé Velázquez (Latin America; Blue Mountain Mystery onwards)
- Bartosz Martyna (Poland; Blue Mountain Mystery - seventeenth season)
- Artur Pontek (Poland; eighteenth season onwards)
- Józef Pawłowski (Poland; Emily Saves the World and Samson at Your Service)
- Juan Navarro Torelló (Spain)
- Anton Savenkov (Russia; Emily Saves the World onwards)
- Petteri Hynönen (Finland; Blue Mountain Mystery onwards)
- Ben Small and John Hasler both give Rheneas a Welsh accent.
- In New Little Engine Rheneas is depicted as an 0-4-2.
- His name is Sudric for "Divided waterfall".
- During production on the fourth season, Rheneas had Sir Handel's face and vice-versa.
- One of Rheneas' models is currently on display at the Hara Model Museum in Japan (previously at Nitrogen Studios).
- The Reverend W. Awdry's model of Rheneas is currently on display at the Narrow Gauge Museum in Tywyn.
- Rheneas was built at Fletcher, Jennings & Co. at Whitehaven, the same place as Skarloey, Captain Baxter, Talyllyn and Dolgoch.
- Nitrogen Studios went to the Talyllyn Railway and took measurements of Rheneas' basis; Dolgoch and other locomotives No.1, No.3, No.4 and No.5 so they could make Rheneas' CGI model for the Skarloey Railway engines return, in the sixteenth season.
- Rheneas has had many modifications throughout the television series. These include:
- Season 5:
- Silver buffers as opposed to grey ones.(Large Scale model only)
- Slightly bigger eyes and nose.
- Season 6:
- Black buffers as opposed to silver ones.
- His whistle is the same as Peter Sam's.
- His model is significantly less weathered.
- Gained slightly thicker eyebrows.
- Season 9
- A permanent tail-lamp.
- His pupils became slightly larger.
- Season 16:
- Accurate bufferbeam to his basis.
- Differently designed wheel-arches.
- Lining was added to his wheel-arches.
- Longer wheelbase.
- Added a visible whistle on his steam dome.
- His cutout windows gained brass frames and contained glass.
- His tail lamp changed to a removable Talyllyn-styled lamp.
- The portholes on the side of his cab became larger.
- Added handrail on top of his boiler as in the Railway Series.
- Riveting detail on the cab and smokebox.
- Added sanding gear.
- Slightly thinner funnel.
- Pupils went back to small.
- Season 17:
- Permanent lamp and lamp irons.
- Season 100:
- His side rods become silver.
- Season 5:
- Rheneas was featured on the 1986 single cover of Oh L'amour, a song by English synthpop duo Erasure.