He is a tumbleweed with a human face.
Role in movie
SpongeBob and Patrick meet Sage on their quest to find Gary in their shared dream (vision). Sage gives them the challenge: put cowboy pirate zombies to rest, giving them the Challenge Coin, which has the courage they seek. Once they pass the challenge, Sage appears in reality, allowing them to see Gary through the Window of Meanwhile. After SpongeBob and Patrick got jailed in Atlantic City, Sage tells them that the courage is not really in the coin, but inside them.
- According to Tim Hill, the role of Sage was written for Keanu Reeves from the beginning, before he even agreed to the part.