Caesars
The Caesars Sportsbook can boast its Vegas retail pedigree, and has one of the more extensive online sports betting presences in the US. The parent company bought British bookmaker William Hill in April 2021.
Unibet
Unibet launched its first online betting service back in 1999, but has had a presence in the US market since mid-November 2019, first going live in Pennsylvania.
WynnBET
WynnBET - the online sportsbook associated with one of the biggest names on the Vegas strip - operates in a number of states and has official betting partnerships with a number of NFL, NBA and NHL teams, as well as Nascar.
FanDuel
FanDuel also began as a fantasy sports competition operator. In 2018 it was acquired by Irish bookmaker Paddy Power Betfair, and within days opened its first retail sports betting outlet at New Jersey's Meadowlands Racetrack.
William Hill
Practically a household name across the UK, William Hill began as a London-based bookmaker, with retail outlets across the land. Today, however, it operates globally online, and in April 2021 its buyout by US-based Caesars Entertainment was completed.
BetMGM
BetMGM is a subsidiary of MGM Resorts International, the hospitality and entertainment giant. BetMGM has official partnerships with the NBA, NHL and MLB, as well as exclusive betting partnerships with numerous NFL teams.
DraftKings
DraftKings started life as a daily fantasy sports (DFS) operator, launching DraftKings Sportsbook in New Jersey on August 1, 2018 - making it the first company to offer legal, online, mobile sports betting services. DraftKings also offers retail sports betting in partnership with casinos throughout the US.