Alexander Blockx (born 8 April 2005) is a Belgian professional tennis player who has risen to become the country's No. 1 singles player, reaching a career-high ATP ranking of world No. 32 in July 2026. Born in Antwerp to Ukrainian-descent parents who were both professional athletes, he started playing tennis at age four and made his mark on the junior circuit by winning the boys' singles title at the 2023 Australian Open and achieving the world No. 1 junior ranking. After turning professional, he broke into the top 500 in 2023, won his maiden Challenger title in Kobe, Japan in 2024, and added a second Challenger title in Oeiras, Portugal in early 2025. In 2025, he secured his first ATP Tour main-draw win, reached the final of the NextGen ATP Finals, and climbed into the top 125, also making his Masters 1000 main-draw debut at the Miami Open. He represents Belgium in the Davis Cup and continues to build on his rapid ascent in the professional ranks.