Denny Johnstone (born 9 January 1995) is a Scottish professional footballer who last played as a striker for Scottish League One club Dumbarton. Johnstone began his senior career with Celtic, leaving the club in 2014 without making a first-team appearance and signing for English Championship club Birmingham City. Johnstone spent time on loan with Conference club Macclesfield Town and League Two clubs Cheltenham Town and title-winners Burton Albion in 2014–15 and spent the 2015–16 season on loan at Greenock Morton in the Scottish Championship. Johnstone departed the Blues and signed for League Two club Colchester United in June 2016.