Artwork has "mysteriously" appeared overnight at Moor Street station in Birmingham.
The painting on a wall at the city centre transport hub depicts the character Emmet from The Lego Movie.
The computer animated film was released earlier this year and was directed and co-written by Phil Lord and Christopher Miller.
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A similar image, which has the Twitter hashtag #LoveEmmet, has also been painted at Marylebone in London to which Chiltern Railways' runs a service from Moor Street.
The Birmingham Post has launched a free app for iPad and iPhone.