Dink & Sam

[Baggins]

 "if it was evil why didn't it kill Graham?"

What's worse than death? Being locked in a cell that has no normal exits where graham can starve to death... Had the blue meanie known about the loose block he wouldn't have put Graham in that cell... Also remember that being caught by the blue meanie leads to a death scene if you didn't befriend Cassima before being caught, or get caught a second time after Cassima frees you.

Besides there have been alot of evil humans who threw people in prisons to die or starve to death in real life in many countries, and throughout history. 

Just because they throw people into prison cells/camps rather than outright killing them, doesn't make them innocent and good instead of being evil... There is degrees of evil...

In anycase we have several descriptions for the monster, between the companion and the game.

Cassima, warns Graham about the creature before he leaves the kitchen in extended dialogue in the book;
"Mordack's monsterous henchman, a creature that prowls around the halls of the castle, never sleeping".

Later after she heard Mordack's henchman catch Graham she helps free him, she warns him not be caught again by the blue meanie, because she does't want to be caught by the creature.

Plus the description for it if you look at it in the game, making it out to be something very scary and nasty(I don't remember the exact description, however)...

In contrast, Dink's descriptions usually make him out to be a comical, innocent, dumb brute who likes music, can be befriended, and who is unaware of his own strength (he'll try to "play" with you, killing you in the process if you don't get his attention with the tamborine).

He vaguely reminds me of the character Lennie in "Of Mice and Men".

[Deloria]

He had the cheese so he wouldn't have starved to death right away. Besides, perhaps Mordack only wanted him out of the way and couldn't be bothered with killing him

[Baggins]

The cheese belonged to the rat, and had Graham missed the fish hook he wouldn't have been able to get it. Not only that the cheese was rotten, it probably would have killed Graham faster. I'm pretty sure the death scene mentions starvation, IIRC(even if you have peas, or cheese in your inventory).

Actually if Mordack catches you in the castle its instant death, he can't be bothered with just sending you to the dungeon cell, and knows the quickest way to get rid of trouble is to wipe it out entirely.

The henchman's job is just prowl the halls looking for intruders, and let them starve to death(apparently he's captured other intruders to the castle as Graham mentions he sees skeletons of other poor victims in the cell in the companion).

Besides the henchman is still described as being vile and nasty in the game though, so I'm pretty sure what the intent of the designers was, that he's an evil creature. There is a major contrast between how the blue henchman is described, and how dink is described in the game.

Plus enough evidence that Cassima doesn't like the creature, so she wouldn't call it a friend.

For all we know the creature could be a scavenger and eat its victims after they die, but who knows :p...

[Yonkey]

The cheese belonged to the rat, and had Graham missed the fish hook he wouldn't have been able to get it.

Is that yet another KQV dead-end or are you being hypothetical?

[Deloria]

It's a dead end.

[Baggins]

Ya, it is another KQ5 dead end, if you forget to get the hook, you can't get the cheese, and therefore you can't beat the game(rotten cheese acts as a catalyst to the strange contraption), :p...

In that game you pretty much can't miss any item or its a dead end.... The only points you can miss as far as I know, is beating the game without tripping the henchman, or bagging Manannan.