While you can find these roles in Discord as well, they primarily describe how users interact with the protocol.
In Poison Ecosystem, users act in one or more of the following roles:
Trader - Uncle
Minter & Shorter - Cook
Liquidity Provider - Wizard
Staker - King
Liquidator - Shark
There are other special auxiliary agents that are required for Poison contracts - Oracle
The Uncle engages in buying and selling pTokens on decentralized exchanges and benefits from price exposure via pTokens.
The Cook is a user who enters into a collateralized debt position (CDP) in order to obtain newly minted pTokens by depositing collateral into the Vault.
The Wizard provides liquidity to decentralized exchanges by pairing pTokens and the trading token such as USDC or ETH and receiving an LP (Uniswap) or SLP (Sushiswap) tokens in return. Certain LP and SLP tokens may be staked in the Brew tab to earn yield in the form of POI$ON.
The King is a user who stakes either pTokens, iPOISON, or LP/SLP tokens in the Brew tab to earn yield in the form of POI$ON.
The Shark is an experienced smart contract sleuth that hunts for Potion vaults with low collateral ratios so that they can be liquidated for a hefty discount.