Well first, we have to determine what a colonizing state is (presumably, you mean overseas as opposed to a land-based empire), when we're talking about (I'm assuming the 16th Century through to the modern day), and how many there have been at any one given time.
The obvious: English/British, French, Spanish, Portuguese, Dutch, Belgian, German, Danish, Swedish, Russian, Italian, Ottoman, Japanese, American
The not-so-obvious:
Austro-Hungarian (Nicobar Islands, etc)
Courlander (Tobago and the Gambia)
Norwegian (a few uninhabited islands in the Arctic and Antarctic)
Scottish (Panama)
Knights of Malta (the Caribbean)
Omani (East Africa and the Persian Gulf Coast all the way to Gwadar)
Moroccan (the Mediterranean, the Sahel, temporary occupation of Lanzarote in the Canary Islands)
Egyptian (North Africa, Sub-Saharan East Africa, the Middle East, the Mediterranean)
Persian (the Middle East, the Persian Gulf, Central Asia)
Chinese (Central Asia, Taiwan, Southeast Asia, Siberia)
Australian (a few Pacific territories)
New Zealander (ditto)
Hawaiian (the Solomon Islands, Samoa)
Mexican (Clipperton, Central America)
Chilean (Easter Island)
Ecuadorian (the Galapagos)
Who else could have had some kind of overseas empire? Possibly Brazil in Africa, Peru in the South Pacific, Tamils or other Southern Indians around the Indian Ocean (as they did in medieval times), maybe Yemen or Ethiopia, perhaps a power based in Southeast Asia.