Ghost

Ghost is the Spirit of Steamer after Stanley kills him. He appears in Five nights at Smudger's 2, 3 and 4

Five Night's at Smudger's 2
Ghost appears in the 4th night cutscene

Five Night's at Smudger's 3
Ghost appears as a secret character. When he appears rise the monitor cameras to get rid of him

Five Night's at Smudger's 4
Ghost first appears in Mission 4: Special cargo after beating the mission Where he is seen entering the empty train's body.

Ghost also appears in Mid sodor origins 6: The sad fate after Steamer falls off of the viaduct