Heidi Costello (also Blissett) is a fictional character from the British Channel 4 soap opera, Hollyoaks, played by Kim Tiddy. She made her first on-screen appearance on 20 July 2010 and made her final appearance in the series on 1 November 2011, after Heidi was accidentally murdered by her father, Silas Blissett (Jeff Rawle), in which he mistakes her for Lynsey Nolan (Karen Hassan).