Gennady Golovkin (born 1982) of Kazakhstan is one of the most feared middleweights in modern boxing history, holding the unified middleweight titles and possessing one of the highest KO ratios in championship history.

Career Highlights

• Professional record: 43 wins, 37 by KO, 2 losses, 1 draw
• Unified IBF, WBA, WBC, and IBO middleweight champion
• 18 consecutive middleweight title defenses — tied for most ever

GGG's combination of high-pressure fighting, elite boxing technique, and pulverizing power made him a nightmare for middleweights throughout the 2010s. His trilogy with Canelo Alvarez is the defining rivalry of modern boxing.

Reference:

Wikipedia: Gennady Golovkin

https://en.wikipedia.org/wiki/Gennady_Golovkin