Photos: REX USA/Paul Grover/Rex; Via Wikipedia.
The pine marten is seriously the spirit animal we all need. Do you see the one up there? It is the cutest. But — and this is key — its adorableness doesn't undercut the fact that it would defend you if necessary. You know, if you summoned it from your wand with an "Expecto Patronum" during a battle with He Who Must Not Be Named.
Rowling's Patronus is in good company: A pine marten also plays an important role in Philip Pullman's His Dark Materials trilogy. Lyra has a dæmon who takes a pine marten as his form.
As of press time, it remains unclear if you can summon Chris Martin with a Patronus charm. (BuzzFeed)