The answer is: Belshazzar

Daniel 5:6 - Belshazzar’s knees knocked together as he was overcome with terror, a physical manifestation of the intense fear he experienced in response to the writing on the wall.

When we talk about Belshazzar, we’re diving into an intriguing moment in Biblical history that echoes throughout time. This king of Babylon held a grand feast, completely unaware of the profound message about to unfold. His knees knocking together wasn’t just a quirky detail; it was a display of pure primal fear, an indicator that divine judgment was at hand. It illustrates a potent truth—fear isn’t always faced with bravery; sometimes, it leaves us trembling.

The famous "writing on the wall," presumably in Aramaic, served as a warning and prophetic message: "Mene, Mene, Tekel, Upharsin." These words would spark curiosity and bewilderment, similar to how modern thinkers—like scholars and psychologists—often muse over human responses to fear and the unknown.

Several kings faced tangible fear in the scriptures, but none like Belshazzar observed with ano-spectacle of writers reminding us that one's self-indulgence can often lead to unforeseen crisis. Even on a more humorous note, think about other "knees knocking" moments throughout the Bible. Goliath seemed tough, but David’s faith had him shaking too—though for very different reasons!

In its essence, this narrative reminds us that humility and awareness of a higher purpose can tame the most terrifying situations, compelling everyone to consider morals beyond mere earthly power. It can even urge us to reflect on our own lives, how fear can grip us, and what light might shine through our jolts of anxiety.