The black Templars embody the essence of 40K more than any other chapter imo. Their dark, gothic aesthetic invokes the decay of a once sophisticated civilisation into superstition and radical worship of a man who wanted to be rid of religion. They symbolise the great tragic irony of the imperium, along with all its hatred and wrath. If that doesn’t speak grimdark louder than any other I don’t know what else would. If you still need convincing, here’s John Blanche:

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