 Tassell was born in Mount Isa, Queensland, Australia, he has Welsh ancestors, and eligible to play for Wales due to the grandparent rule.Tassell won 11 caps for Wales in 2000–2004 while at Salford, Wakefield Trinity and Swinton 6-tries 24-points.Tassell played in the 2000 Rugby League World Cup for Wales and won man of the match honours in the first round game versus the Cook Islands in which he scored a hat trick.