Robert Richard Cornthwaite (born 24 October 1985) is an Australian former soccer player. At 1.95 m, Cornthwaite is the joint second tallest player to have represented the Australia national association football team, behind Zeljko Kalac and alongside Eli Babalj and Sasa Ognenovski.

Robert joined the Malaysian Super League outfit Selangor in early 2015 and scored a few goals for the club. He was selected to play for Malaysian XI in a friendly match against Tottenham Hotspur in July 2015. In January 2016 his contract with Selangor was continued after Selangor fans forced the Football Association of Selangor to continue his contract by using the social media. On 9 July 2016, Cornthwaite was released by Selangor.

On 16 January 2018, Cornthwaite signed a contract with Malaysia Super League club Perak on a one plus one-year deal. Cornthwaite announced his immediate retirement from football on 4 June 2018, halfway through his Perak contract.