Jan Jacobus "Sonny" Silooy (born 31 August 1963) is a Dutch former professional footballer and football manager. His last team as a manager was United Arab Emirates club Al Shabab under 19. His most successful time as a player was in his period with Ajax. He won seven Eredivisie titles, four KNVB Cups, three Johan Cruyff Shields, one UEFA Cup Winners' Cup, one UEFA Cup, one UEFA Super Cup and one Intercontinental Cup.

Silooy was born in Rotterdam. He played as a right or central defender and is one of the legends of Ajax, where he made his debut on 3 May 1981, playing over 250 league games for the Amsterdam club in two separate periods. Silooy also played for Matra Racing, Arminia Bielefeld,^[2] De Graafschap and the amateurs of GVV Unitas from Gorinchem. He played in the 1996 UEFA Champions League Final against Juventus, but missed a key penalty in the shootout which Ajax ultimately lost.^[3]

Silooy, a member of the Netherlands national team's squad at the 1983 FIFA World Youth Championship, obtained 25 caps,^[4] including eight appearances in Euro 88 qualifying, but never played in a major international competition.

Silooy was also coach of the Jong Ajax youth academy and juniors team.^[5] In 2010, he was appointed as head coach of new branch Dayton Dutch Lions.

He left Dayton Dutch Lions to become an assistant coach with the Major League Soccer club D.C. United.^[6] In 2015 he was appointed as head coach of Al Shabab under 19.