The ghost of Christmas Yet To Come is described as a "solemn phantom," creeping along the ground like a mist. This ghost is different from the others in its silence, which gives it an awful, terrifying aspect. It is "shrouded in a deep black garment," which "left nothing of it visible" except its outstretched hand. The mysterious nature of this last spirit, and the terrible prospect of seeing what the future might hold, actually causes Scrooge to quake with fear. Yet the spirit is not ignoring Scrooge; it notices his fear and pauses to wait for him to gather his courage. That pause is perhaps the most terrible of all: Scrooge imagines the unseen eyes hidden behind the shroud that must be watching him closely.
It's common to visualize this ghost in the same way we think of the spirit of death or the "Grim Reaper." Although the spirit has no scythe, his clothing and silence suggest suggests Scrooge's own legacy. The scenes the spirit shows Scrooge have to do with the aftermath of his own death, so in a way the ghost's shroud and silence is akin to Scrooge's own wearing of the shroud after death, and his own deathly silence. In fact, when spirit takes its leave, after showing Scrooge his own grave, his shroud seems to melt into Scrooge's own bedpost, as if the spirit somehow was an emanation of Scrooge himself.