8) Chris Ashton
Ashton switched codes aged 20, just two years after his senior debut in League. But he took Rugby Union by storm.
The then teenager was an impressive mainstay of the Wigan side during a challenging period, but his impact in Union was instant – he scored with his first ever touch of a ball in the sport after coming on as a substitute for Northampton in a 44-11 Division One win over London Welsh.
He would eventually go on to notch a whopping 39 tries in 25 appearances as Northampton secured promotion back to the top flight in 2008, where he would again impress, subsequently earning an England call up in 2010.