Hank Griffin is Nick's homicide partner who, like Juliette, was not aware that Nick is a Grimm until recently. He is somewhat sarcastic at times, and has gone through at least four marriages by the time the series begins, but is nevertheless still Nick's best friend in the human world.

Hank starts to notice the strange occurrences that have been happening in Portland, and even in some of the cases he works on them with Nick. He was even used by Adalind to get closer to Nick, by consuming a "love sick" potion that caused him to develop obsessive behavior towards her. He accidentally runs into a transformed Monroe, who was leading search dogs away from his friend. Combined with seeing their dead suspect change back into human form from an experimental drug, Hank begins to have nightmares and heightened paranoia when he is home, and is even seen falling asleep with a fire arm.

Hank starts to doubt whether he can continue police work given his state of mind. When searching for the missing daughter of an old friend from high school, Hank learns his old friend is a Coyotl and Nick is a Grimm. After all is said and done, Hank tells Nick that he is comfortable now knowing the truth, reflecting that, while he may be crazy, at least there is someone else who is crazy as well.