The best guide by far to domestic breeds of cow is the Breeds of Livestock Project from Okhlahoma State University. This is, however, a list of domestic cattle only, so that although it does include the Slovenian Cika, the Xinjiang Brown, and RX3, it doesn't include wild varieties of cow.
In Britain, we have the white Chillingham Wild Cattle who live in Northumberland and are apparently "truly wild, and potentially dangerous".
The Yak is a large hairy kind of cow, originating in Asia. They can be bred with domestic cattle to produce a dzo. There are also domestic Yaks, which are a lot smaller.
The Bison lives in North America, where it is also known as a buffalo, and Europe, where it also goes by the name of wisent or zubr. The water buffalo has huge horns and lives in Asia, in water. Like the Yak, there is a domesticated variety.