Isla Lang Fisher (/ˈaɪlə/; born 3 February 1976) is an Australian actress. Born in Oman to Scottish parents who moved with her to Australia during her childhood, she began appearing in television commercials. She became prominent for her portrayal of Shannon Reed on the Australian soap opera Home and Away (1994–1997), for which she received two Logie Award nominations.

Fisher transitioned to Hollywood with a supporting role in the comedy horror film Scooby-Doo (2002) and has since starred in films such as Wedding Crashers (2005), Wedding Daze (2006), Confessions of a Shopaholic (2009), Bachelorette (2012), The Great Gatsby (2013), Now You See Me (2013), and Nocturnal Animals (2016). Her other credits include I Heart Huckabees (2004), Definitely, Maybe (2008), Keeping Up with the Joneses (2016), Tag (2018), and The Beach Bum (2019), in addition to voice roles in animated films such as Horton Hears a Who! (2008), Rango (2011), Rise of the Guardians (2012), and Back to the Outback (2021).