1980-1981: Unknown 1981-1982: Unknown 1982-1983: Unknown 1983-1984: Unknown 1984-1985: Unknown 1985-1986: Slytherin wins the House Cup, Gryffindor wins the Quidditch Cup 1986-1987: Slytherin wins the House Cup, Hufflepuff, Ravenclaw or Slytherin won the Quidditch Cup 1987-1988: Slytherin wins the House Cup, Hufflepuff, Ravenclaw or Slytherin won the Quidditch Cup 1988-1989: Slytherin wins the House Cup, Hufflepuff, Ravenclaw or Slytherin won the Quidditch Cup 1989-1990: Slytherin wins the House Cup, Hufflepuff, Ravenclaw or Slytherin won the Quidditch Cup 1990-1991: Slytherin wins the House Cup, Hufflepuff, Ravenclaw or Slytherin won the Quidditch Cup 1991-1992: Gryffindor wins House Cup; Slytherin won the Quidditch Cup 1992-1993: Gryffindor wins House Cup; Quidditch cancelled due to Chamber of Secrets 1993-1994: Gryffindor wins the House Cup and the Quidditch Cup 1994-1995: House Cup winner unknown; Quidditch cancelled due to Triwizard Tournament 1995-1996: House Cup winner unknown; Gryffindor wins the Quidditch Cup 1996-1997: House Cup winner unknown (likely Gryffindor); Gryffindor wins the Quidditch Cup 1997-1998: Unknown 1998-1999: Unknown