Katsuhiko Sumii (角居 勝彦 Sumii Katsuhiko) (born March 28, 1964, Kanazawa, Ishikawa) is a Japanese horse trainer. He trained the first and second placing horses in the 2006 Melbourne Cup, Delta Blues and Pop Rock.
- Delta Blues - Won Melbourne Cup (Aus G1 2006), Kikuka Sho (Japanese St. Leger, JRA Domestic GI 2004), Stayers Stakes (JRA Domestic GII 2005).
- Kane Hekili - Won Japan Cup Dirt (JRA Domestic GI 2005, 2008), February Stakes (JRA Domestic GI 2006), Kawasaki Kinen (NAR Domestic GI 2009), Tokyo Daishoten (NAR Domestic GI 2008), Japan Dirt Derby (NAR Domestic GI 2005), Derby Grand Prix (NAR Domestic GI 2005）. 4th Dubai World Cup (UAE G1 2006).
- Pop Rock - Won Meguro Kinen (JRA Domestic GII 2006 and 2007). 2nd Melbourne Cup (Aus GI 2006), Arima Kinen (JRA Domestic GI 2006）, Japan Cup (JRA GI 2007).
- Friendship - Won Japan Dirt Derby (NAR Domestic GI 2006).
- Vodka - Won Hanshin Juvenile Fillies (JRA Domestic GI 2006), Tokyo Yushun (Japanese Derby, JRA Domestic GI 2007), Yasuda Kinen (JRA GI 2008, 2009), Tenno Sho (Autumn) (JRA GI 2008), Victoria Mile (JRA GI 2009). Japan Cup (JRA GI 2009), 2nd Oka sho (Japanese 1000 Guineas, JRA Domestic GI 2007), Victoria Mile (JRA Domestic GI 2008).
- Tall Poppy - Won Hanshin Juvenile Fillies (JRA Domestic GI 2007), Yushun Himba (Japanese Oaks, JRA Domestic GI 2008).
- Victoire Pisa - Won Satsuki Sho (Japanese 2000 Guineas, JRA GI 2010).