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“Because of a big boulder. I think it's watching me."
"How can it be? Boulders don't have eyes."
"That's as may be Percy, but there's something strange about this one.”
Rusty and Percy[src]

Boulder is a giant mysterious boulder who lives up high in the mountains of Sodor.


Thomas & Friends

Its home was found by the Skarloey Railway, who then preceded to build a quarry on the cliff-side below it. Rusty was suspicious of it and thought that it may have been watching him. Later, the drilling into the mountain by Thumper caused vibrations that shook Boulder loose from its perch and sent him down onto the tracks, creating a path of destruction along the Skarloey Railway, finally stopping by destroying the standard gauge sheds. After this, Sir Topham Hatt closed the quarry and had Boulder moved to a new mountain, close by the yards. It still stands there to this day. Rusty is sure that, on a clear night, it’s gazing high up at the mountains in the distance and that its sighs are being carried on to the wind where it once used to stand, proud and silent.

Boulder is perfectly spherical and has moss clinging to him in some places. A mysterious face sometimes appears on it.


Boulder’s personality is described as proud and silent. He is extremely vengeful and easily angered; the construction of the new quarry below him infuriated him to the point where he went on a destructive rampage that ultimately forced the quarry’s closure.


Official Description

From Official Media:[1]

Boulder: Boulder lived high in the mountains of Sodor above a new quarry being built. During the construction, Thumper shook the mountain a little too much, and Boulder fell onto the tracks. After he chased Rusty, Skarloey and Percy, Sir Topham Hatt decided to close the quarry and move Boulder to a hill close by the yards, where he now lives.

Fun Fact: Rusty is sure that on a clear night, Boulder gazes up at the mountain where he once lived, and sighs.


  • Boulder's face is based on Gordon's sad face mask.
  • Boulder had a replica built for display at the Hara Model Railway Museum. This can be proven by the differences in the ridges between the replica and the official prop.