Simeon Oscar Williamson is an English bobsledder and former track and field sprinter who specialised in the 100 metres. Williamson, a London native, is the second cousin to 2008 Beijing Olympics silver medalist British high jumper Germaine Mason. He is coached by Lloyd Cowan, and his athletics club is Highgate Harriers. He is a former British 100 metres champion.

The 2005 European Athletics Junior Championships was the 18th edition of the biennial athletics competition for European under-20 athletes, which was held in Kaunas, Lithuania on 21–24 July.