While not a major character in On Golden Pond, Charlie is significant because he has known the Thayer family for years and years. He is the local postman, and he is described as looking older than he actually is, with a face that has aged due to the amount of time he spends outdoors.

The other thing that makes Charlie significant is his feelings for Chelsea. He's just two years older than her, and these feelings go back many years. He is depicted as perhaps a little less smart than other characters because he does not always pick up on Norman's sarcasm.

We aren't told much more about Charlie, and we are left to infer that perhaps his significance lies in portraying Chelsea as a likable and desirable character despite the difficulties that she had in pleasing her father as a child.

His liking for Chelsea is arguably juxtaposed against the ambivalence that she felt from her father while growing up. It is revealed in act two that while Chelsea always worked really hard to please her father, she never felt that she met up to his high standards. To Charlie, on the other hand, Chelsea is far more than adequate.

Unfortunately for Charlie, when Chelsea shows up to visit for Norman's birthday, it is with her new boyfriend (and soon to be husband), Bill Ray.