Stefan Koubek, Austrian tennis player
Stefan Koubek (born 2 January 1977) is a retired tennis player from Austria. Koubek played left-handed with a double-handed backhand. His idol when growing up was Thomas Muster. Koubek won three titles, two of which came on hardcourts; despite this, he said his favorite surface was clay.Koubek reached the quarterfinals of the 2002 Australian Open and the 2002 Hamburg Masters, attaining a career-high singles ranking of World No. 20 in March 2000. Koubek tested positive for glucocorticosteroids at the 2004 French Open after receiving an injection for an injured wrist; he was subsequently suspended for three months.

His nickname is Cooley or Stef.