AACTA Award for Best Original Screenplay

The AACTA Award for Best Original Screenplay is an award presented by the Australian Academy of Cinema and Television Arts (AACTA), for an Australian screenplay "written directly and originally for the screen". Prior to the establishment of the Academy in 2011, the award was presented by the Australian Film Institute (AFI) at the annual Australian Film Institute Awards (more commonly known as the AFI Awards). It was first handed out in 1978 when the award for Best Screenplay (which was first presented at the 1974-75 awards) was split into two categories: Best Original Screenplay and Best Adapted Screenplay. The award has since been presented intermittently from 1978-1979, 1983-1987, 1989, 1993-2006, and then from 2008-present.

Winners and nominees
In the following table, the years listed correspond to the year of film release; the ceremonies are usually held the same year. The films and screenwriters in bold and in yellow background have won are the winners. Those that are neither highlighted nor in bold are the nominees. When sorted chronologically, the table always lists the winning screenplay first and then the other nominees.Winners and nominees by year:
 * 1978:
 * 1979:
 * 1983:
 * 1984:
 * 1985:
 * 1986:
 * 1987:
 * 1989:
 * 1993:
 * 1994:
 * 1995:
 * 1996:
 * 1997:
 * 1998:
 * 1999:
 * 2000:
 * 2001:
 * 2002:
 * 2003:
 * 2004:
 * 2005:
 * 2006:
 * 2007:
 * 2008:
 * 2009:
 * 2010:
 * 2011: