Stanislaus "Stan" Henricus Christina Valckx (born 20 October 1963) is a Dutch former professional footballer who played as a central defender.

After starting professionally with VVV-Venlo (second division), he moved in 1988 to Eredivisie club PSV Eindhoven, being instrumental in the conquest of three leagues and two Dutch Cups – in the 1991–92 season, he scored four goals in 28 matches as the team renewed their domestic supremacy.

In 1992, Valckx, aged 28, moved abroad, to Sporting Clube de Portugal, helping the Lisbon side to the Portuguese Cup three years later, although he did not play in the final against C.S.

Marítimo as in October 1994 he had already returned to his country and PSV, where he won one more league and another domestic cup before retiring in June 2000 at nearly 37 years of age, with more than 500 official appearances to his credit.

In 2008, he got into a conflict with general manager Jan Reker about the influence and role of player agent Vlado Lemić at the club;[2][3] the following year, in the same capacity, he joined China's Shanghai Shenhua FC.