Who was the commander of the king's guard sent to execute the wise men of Babylon?

Answer: Arioch

Arioch, commander of the king's guard, went out to execute the wise men, and Daniel spoke to him with discretion and tact.

“When Arioch, the commander of the king’s guard, went out to execute the wise men of Babylon, Daniel responded with discretion and tact. “Why is the decree from the king so harsh?” he asked. Then Arioch explained the situation to Daniel.”— Daniel 2:14-15 (BSB)