Here are some popular coins paired with Bitcoin (BTC):
1. *ETH/BTC*: Ethereum-Bitcoin pair
2. *LTC/BTC*: Litecoin-Bitcoin pair
3. *BCH/BTC*: Bitcoin Cash-Bitcoin pair
4. *XRP/BTC*: Ripple-Bitcoin pair
5. *DOGE/BTC*: Dogecoin-Bitcoin pair
These pairs are commonly traded on cryptocurrency exchanges.