Rosie

Rosie is a lively little tank engine who idolizes Thomas. She works as both a shunting engine and a mixed traffic engine.

Trivia

 * Rosie is the first engine of several things:
 * The first engine of an American class introduced in the television series and the second such engine (after Stanley) introduced in the franchise overall.
 * The first engine in the television series to have their debut livery changed permanently and the second character in the television series overall, the first being S.C. Ruffey.
 * The first engine in the television series to receive a number who did not already have one.
 * The first engine in the television series to be lettered for the North Western Railway. She is the second in the franchise overall after Emma.
 * Rosie's model is currently on display at Drayton Manor. Sometime in 2017, a part of her siderod had broken off.
 * In Red for Rosie, one illustration incorrectly depicts her with a tender.
 * Most merchandise lines depicted Rosie without the lip gloss and blush that she had worn prior to the twenty-first season.
 * Rosie's whistle is a higher pitched version of Thomas'.
 * A magazine fact file states that she works on Thomas' Branch Line, although she is yet to be seen doing so in the television series.
 * The My First Thomas & Friends' Railway Pals variant of Rosie was the first piece of merchandise to introduce her in her new red livery.
 * Since her debut, Rosie has appeared in every season and special except The Adventure Begins, which was set before she arrived on the railway, and the twentieth season, possibly due to her model being reworked for the twenty-first season and Journey Beyond Sodor.
 * Rosie has both her whistle and connecting rods in different positions compared to her prototype:
 * Rosie's whistle is positioned behind her rear dome whilst her prototype has its whistle positioned on the right side of the middle dome.
 * Rosie's connecting rods are attached to her middle driving wheels whereas her prototype has its connecting rods attached to the rear driving wheels.
 * Her funnel is also taller than her basis.
 * Rosie has had a few modifications throughout the television series, which include:
 * Season 12:
 * Her tail-lamp was removed.
 * Season 13:
 * Her face became slightly smaller.
 * Her funnel and steam pipes became thinner.
 * Her lamp-irons were removed.
 * A detail on her coal bunker had been pushed in.
 * Mid-Season 17 (starting with Percy's Lucky Day onwards):
 * She gained a permanent headlamp of the same design as Ferdinand's, mounted in front of her funnel.
 * Tale of the Brave:
 * She regained her tail-lamp.
 * Season 21:
 * She received a new cherry red livery with "NWR" painted on her side tanks and the number 37 painted under her cab windows.
 * She lost her lip gloss and blush.
 * She gained rivets across her cab, side tanks, smoke box, cylinders and the sides of her buffer beam.
 * Rosie is numbered 37 as of the twenty-first season, this number was likely chosen as she is the 37th standard gauge engine introduced in the television series.
 * According to SIF, Rosie was intended to have at least one other episode in the twenty-first season. This episode, along with seven others, were cancelled to make way for production of the twenty-second season.