“You can never be too rich or too thin.”

Wallis Simpson, the Duchess of Windsor, wasn’t referring to fine watchmaking when she uttered her famous quote, but she may as well have been. Ever since the financial crisis of 2008 stoked desire for classic, understated timepieces, watchmakers have done battle to achieve record-breaking slimness. As a result, the category is now bursting with slender styles equipped with wafer-thin movements. Here, we survey some of the thinnest watches on the market, whose complicated mechanisms make clear that a wristwatch with a low profile can still pack a powerful punch.