Dr. Left

Oracle of Seasons
Dr. Left is a Cucco-studying biologist living in a southeastern residence of Horon Village in Oracle of Seasons. In return for lighting his torch with Ember Seeds, he rewards Link with a Cuccodex, the first item in the trading sequence. Whenever Link speaks with him afterwards, the doctor will feed him seemingly random facts about characters or monsters found through Holodrum. All his tidbits of knowledge begin with the characteristic phrase, "My books tell me..."

The Minish Cap
Dr. Left later appears in The Minish Cap. Instead of researching Cuccos, he instead seems more interested in learning about the mysterious Picori race. He is one of the people who has an overdue library book and Link will have to find a way to get the book back which is in Dr. Left's house. Before Link has to find the overdue library book, Dr. Left will not let him into his house as he is studying all the time. 

Trivia

 * The name "Dr. Left" is a pun on a nearly-identical character who appeared in a previous game, Mr. Write. Of course, the pun on the words write being pronounced as right, and right and left being opposites.
 * It can be presumed that this character is in some way related to Sim City's Dr. Wright, not only due to the obvious link in last name, but also an uncanny likeness in hairstyle and color.