Jim the Fish
From Tardis Wiki, the free Doctor Who reference
Jim the Fish was a friend of the Eleventh Doctor and River Song, whom they met on one of their adventures. When they met him, he was building a dam, and was still doing so some time later when the Doctor checked up on him. (DW: The Impossible Astronaut)
River Song's diary contains an entry called "The Ballad of Jim the Fish," which can be read when all the pieces of that particular page are collected (VG: Doctor Who: The Eternity Clock)
