1. In Baseball: The "third robin" might refer to a third round of games in a round-robin tournament format.
2. In Literature: There's no established character in literature specifically called "the third robin." It's possible you're thinking of a specific story or context where this phrase is used.
3. In a Different Context: Could you provide more information about where you heard the phrase "third robin?" Knowing the context would help determine what it refers to.
Please clarify your question, and I can help you figure out who or what the "third robin" is.