As an AI language model, I don’t have access to real-time data. Additionally, determining the “most successful” rebrands in the gambling industry can be subjective and depend on various factors such as financial performance, customer reception, and market impact. However, here are ten prominent rebrands in the gambling industry in recent years; their success may vary:

1. The Stars Group rebranding to Flutter Entertainment
2. GVC Holdings rebranding to Entain
3. Paddy Power Betfair rebranding to Flutter Entertainment
4. William Hill rebranding their online operations to William Hill US
5. BetBright rebranding to 888sport
6. Sky Betting and Gaming rebranding to Sky Bet
7. Full Tilt Poker rebranding to Full Tilt Gaming
8. Bwin.Party Digital Entertainment rebranding to GVC Holdings
9. Roxy Palace Casino rebranding to Mega Casino
10. Betway rebranding to Dream Bingo

It’s essential to note that this list may not include the most up-to-date information, as rebrands take place regularly in the industry. For the latest information, it’s best to refer to reliable gambling industry news sources.