USA:
Season 1 (2011) - Melanie Amaro
Season 2 (2012) - Tate Stevens
Season 3 (2013) - Alex and Sierra
United Kingdom:
Season 1 (2004) - Steve Brookstein
Season 2 (2005) - Shayne Ward
Season 3 (2006) - Leona Lewis
Season 4 (2007) - Leon Jackson
Season 5 (2008) - Alexandra Burke
Season 6 (2009) - Joe McElderry
Season 7 (2010) - Matt Cardle
Season 8 (2011) - Little Mix
Season 9 (2012) - James Arthur
Season 10 (2013) - Sam Bailey
Season 11 (2014) - Ben Haenow
Season 12 (2015) - Louisa Johnson
Season 13 (2016) - Matt Terry
Season 14 (2017) - Rak-Su
Season 15 (2018) - Dalton Harris
Season 16 (2019) - Dalton Harris
Australia:
Season 1 (2005) - Altiyan Childs
Season 2 (2007) - Natalie Gauci
Season 3 (2010) - Samantha Jade
Season 4 (2012) - Reece Mastin
Season 5 (2013) - Dami Im
Season 6 (2014) - Marlisa Ann Punzalan
Season 7 (2015) - Cyrus Villanueva
Season 8 (2016) - Isaiah Firebrace
Italy:
Season 1 (2008) - Marco Carta
Season 2 (2009) - Matteo Becucci
Season 3 (2010) - Marco Mengoni
Season 4 (2011) - Francesca Michielin
Season 5 (2012) - Chiara Galiazzo
Season 6 (2013) - Michele Bravi
Season 7 (2014) - Lorenzo Fragola
Season 8 (2016) - Sofia Tornambene
Spain:
Season 1 (2007) - María Villalón
Season 2 (2008) - Míriam Rodríguez
Season 3 (2009) - Elías Jaude
Season 4 (2010) - Paula Rojo
Season 5 (2011) - Juan Carlos Campos
Season 6 (2012) - David Lafuente
Season 7 (2013) - Ruth Lorenzo
Season 8 (2018) - Ana Mena
Season 9 (2019) - Natalia Lacunza
Please note that this list is not exhaustive and there may have been additional seasons and winners not included here.