Captain Oats is Seth Cohen's toy horse and an object he is quite fond of.
Throughout the Series
Before the arrival of his adopted brother Ryan Atwood, Captain Oats was the only "true friend" of Seth, which explains a lot about the young Cohen's personal life. In Season 1, Anna Stern, Seth's ex-girlfriend and close friend, writes a comic book for Captain Oats and Seth as a Chrismukkah present.