Famous women in history (e.g. Madame De Pompadour, the rich/wealthy of Venice) were often regarded as trendsetters in Europe for bring certain styles into fashion. Do any male counterparts exist?

"Trendsetter" is a word that I don't like using outside of the contemporary context (along with "fashion icon"), because it implies a perfect analogy with modern culture. A twenty-first century trendsetter is photographed with a new bag and highlighted on a gossip site, or promotes it herself on Instagram, and millions of "ordinary people" pick up the new style - but in the eighteenth century, there was only a very limited form of mass media. The sort of printed matter available to most people (broadside ballads, newspapers) completely ignored matters of fashion, while periodicals dedicated to or including fashion, like the French Galerie des Modes or the English Lady's Magazine, were only available to a limited, elite audience: individual society figures were simply not able to make the kind of splash that a modern trendsetter can.

And at the same time, tying individual figures to fashions that do appear in the elite journals is not an easy task. For the most part, the gowns, hats, and other accoutrements are presented as outfits that a writer for the publication saw on the street in fashionable locations like the gardens of the Palais-Royal, the Longchamps Racecourse, Bath, Ranelagh Gardens, Vauxhall Gardens, etc. Very occasionally they were attributed to a particular theatrical production - the Beaumarchais play The Marriage of Figaro premiered in Paris in 1784, for instance, and the clothing worn by various actors inspired jackets, waistcoats, hats, and so on à la Figaro, à la Almaviva, à la Cherubin, à la Suzanne. This less represents any specific actor being a trendsetter (with the implication of individual style and attention that the words carries), and more reflects the complex relationship between the fashion industry, the stage, and the receptive audience. /u/kittydentures wrote a great description here regarding the dissemination of the chemise gown in France and England, which I think will show you how the dress itself managed to wield more power than the wearer at times. Both of us made the point in our responses to the same question that Marie Antoinette, often modernly called the ultimate trendsetter and fashion icon of her time, was in fact so fashionable because her Parisian modiste, Rose Bertin, brought her the most up-to-date styles - not because what she wore was immediately copied far and wide.

So, I think I've made the point that I don't view "trendsetter" as a useful or accurate label for historical figures in general. What about the men?

Analyses of historical figures as trendsetters are typically shallow, and its that shallowness that highlights their sexism. Women are declared as having been trendsetters if they were known for spending money on clothes, or for exercising power, or simply for being names that are still remembered, because women are inherently connected with fashion - but people don't do this with men. If a man's remembered for his career, it's assumed that his career itself is of interest; if he's connected with an innovation or a style, it's just that style, and the "trendsetter" label is used almost sarcastically.

In the period you've laid out, really the only man given credit as a fashion innovator is Beau Brummell. He's typically made out to have "invented modern menswear" by transforming the suit of the late eighteenth century into the suit of the early nineteenth, and pioneering a trend for unstyled masculine hair and clean, un-made-up faces. I addressed the problems with this myth here:

We see men begin to adopt soberer colors in the 1770s, and this becomes more common/fashionable in the 1780s, and more so in the 1790s. Brummell's own sense of style was part of a wider trend, rather than springing fully formed from his head and changing the world. (This is the big problem with holding up Great Men/Women in fashion history in general - they're nearly always responding to wider trends, often along with a number of other people; "helped to popularize" is a better phrase to use than direct attribution.)

The white cravat had begun to return to fashion before Brummell became a figure, beginning to supplant the stock (worn around the neck with the pleated/creased section in front) and jabot (a ruffle sewn down the front of the shirt) in the 1780s. Colored neckwear, the modern norm, didn't really become standard until the very late 1820s.

Women started to abandon hair powder and adopt more "natural" hairstyles in the 1780s; men soon followed. (Powder was killed off as a mark of fashion - rather than conservatism or servanthood - in the UK in the years following the British Duty on Hair Powder Act of 1795, which required each individual who wanted to wear powder pay a guinea tax.)

Even during Brummell's period of influence (~1796-1813 - mostly before the Regency, you'll notice), men often fashionably wore dark coats with light breeches and light or colored waistcoats - as Brummell even is in the famous drawing of him - a far cry from the modern matching three-piece suit.

From the mid-1810s through the 1840s, the fashionable man had a narrow waist and something like an hourglass figure, accentuated by the cut of the coat. Colorful waistcoats also continued to be worn until ca. 1870.

I don't exactly quibble with the notion of the Great Masculine Renunciation itself - there certainly was a shift in what aspects of fashion were considered appropriate for men. The problem is that it is often represented as happening all at once, with Brummell at the reins, when it was a slower process and involved different standards changing at different times, sometimes moving back and forth. The concept itself dates to the 1930s, a time when fashion history was in its infancy and often handled as a kind of side dish by scholars whose expertise was in another field (in this case, John Flügel, a psychologist/psychoanalyst); it needs some complication and revision.