Rob was diagnosed with motor neurone disease in 2019, a debilitating condition that affects the nerves and the brain. Since that date, he has tirelessly campaigned to raise awareness of the disease - and will have a specialist centre named after him built in the city.
Today, fans left hand-written notes, flowers and shirts at the stadium - and many expressed deep sorrow following the sad news.
Here are 23 photos of the tributes and some of the people who left them -
Joe Strother, 22, a big fan of the Leeds Rhinos, remembered watching Rob playing as a child. He said: "He was a local hero. He showed so much fight and determination right until the end. A lot of happy memories." | National WorldPhoto: National World
This was one of many tributes left at Headingley today. It thanked Rob "for the memories" and described him as "an inspiration". | National WorldPhoto: National World
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