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Ronald III
From Discworld & Pratchett Wiki
An entirely dislikeable and throroughly objectionable monarch, Ronald the Third of Lancre is chiefly remembered as a bit of unfortunate rhyming slang - something you tread in: Ronald the Third = turd (colloquial English for, well, excreta).
Annotation
[Who clearly resonates with Richard III, as demonized by Shakespeare and other supporters of the TUDOR MYTH]