This is a cute logo that manipulated an "a" into a figure of a penguin. I liked that this logo was extremely simple, but served two purposes: to stand for "antarctica" and to make an association between the continent and its well known animal inhabitant.
Owl Logo by Sean Farrell
Bird Logo by 3ab2ou on Creative Market
40 Examples of a Single Letter Designed Logo
Bittone Equipment Services
42 Beautifully Designed Single Letter Logos - PelFusion
Richard Fonteneau - Pesquisa do Google
45 Artistically Designed Single Letter Logo Designs | Free and Useful Online Resources for Designers and Developers