Hank the Cowdog is a long-running American series of children's books written by John R. Erickson and illustrated originally by Gerald L. Holmes, and later by Nikki Earley. The books follow Hank, a dog who views himself as the "Head of Ranch Security". Hank suffers a superiority complex, and thinks he is smarter than everybody else; his intelligence is limited to that of the average dog. In each book Hank and other characters must deal with several events, issues and mysteries that occur at their Texas Panhandle home in Ochiltree County. The name of the ranch is never mentioned in any of the stories. The series began in 1982, with a couple of short stories about Hank and his friends; since then, 84 printed books and seven audio-only books have been published. Hank the Cowdog was previously published via Maverick Books, with Puffin Books holding the current American publishing rights in English. Each book features songs that Erickson performs on the audiobook editions. The series has received awards and critical acclaim, and the books have sold more than eight million copies worldwide. It has been published in several languages including Spanish, Danish, Persian, and Chinese. In the 1980s, the first book was adapted into an animated segment for CBS Storybreak.

Teaching programs are available for the series via Maverick Books and a story entitled The Case of the Dancing Cowboy was serialized in 2002, in several American newspapers.

Characters Hank: Hank is the main character and narrator of each story in the Hank the Cowdog adventures. Hank is the only character to appear in every single story in the series. Hank claims to be a "purebred top-of-the-line blue-ribbon cowdog", and that may in fact be true. According to the official Hank The Cowdog Website, Hank is based on a real Australian Shepherd named "Hank". He styles himself as the "Head of Ranch Security" and conducts security sweeps and nightly patrols. However his real task is to serve as the assistant to Slim and Loper in herding cattle. Hank has a superiority complex which causes him to have an inflated sense of his own intelligence, strength, courage and attractiveness. As a result of this, Hank frequently finds himself in sticky situations, usually of his own creation. Much of the humor of the series comes from Hank as narrator shamelessly attempting to make himself seem more competent with hindsight than he really was, but the reader is rarely fooled. Despite his flaws Hank is deeply loyal to his family and the ranch community and usually rises to the occasion at the moment of true crisis. He has a sister named Maggie, who has four puppies named Barbara, Roscoe, April, and Spot. She is much more refined than her brother and sees Hank as a disappointment and a bad influence on his nieces and nephews. She tries to get him to leave whenever he visits her, all the while trying to be nice. Hank is based on an Australian Shepherd named Hank that was owned by a neighbor of Erickson's when he was managing a ranch in Oklahoma. The neighbor wanted to use the dog to help with the cattle but the dog was not trained and proved a hassle.

Drover: Drover is a younger dog who lives on the ranch with Hank as his best friend. Hank refers to him as his assistant, or as a "little mutt" when Hank is angry with him. Unlike Hank, Drover has no delusions of grandeur and enjoys spending most his time staying out of trouble and sleeping (16 hours a day according to Hank), often engaging in useless tasks he invents for himself. Drover is lazy and tends to be wimpy and not helpful when it comes to helping Hank with tasks. In The Case of the Car-Barkaholic Dog, for example, Hank observes that while he is helping the cowboys with the cattle herding, Drover spends the afternoon chewing on an old horn, buries it, and then promptly forgets where it is buried. He is also unashamedly timid, and frequently avoids "the call of duty" by pretending to have a bad leg. Drover has a great deal of curiosity and often asks Hank obscure questions such as "Why does the moon rise in the evening and set in the morning?" Hank rarely knows the answer to these questions, but this doesn't stop him from providing ones. Drover often appears to have more common sense than Hank, which allows him to avoid getting into many of the same catastrophes Hank creates for himself. However, he is not very smart, frequently taking figures of speech literally, and misunderstanding the military jargon which Hank often uses. Drover appears in every story in the series, with the exception of A1: The Homeless Pooch.

Sally May: Sally May is married to High Loper and the mother of Little Alfred and Baby Molly. She is a housewife who enjoys parties and often serves as a civilizing check on her cowboy husband. She is often high-strung, particularly in "The Case of the Killer Stud Horse" and "The Phantom in the Mirror", when she has company coming over. Pete the Barn Cat is her favorite pet and she is affectionate towards both him and Drover. She dislikes Hank, however, and frequently gets angry at him for coming into her yard, her house or fighting with Pete. Her most common response when angered is to try to hit him with her broom. Despite this Hank often seems to think that Sally May secretly respects him. In reality, her feelings fluctuate between disgust and temporary respect as Hank usually follows up his shenanigans with an act of heroism.

High Loper: Owner of the ranch, High Loper (his last name is never given) is an old-fashioned cowboy who enjoys roping, riding and working his ranch. While Loper never wants to leave the ranch and is loath to go out of town, he is far from a workaholic, settling for shoddy workmanship on many of his projects and pawning the dirty work onto his ranch hand, Slim Chance. His more anti-social cowboy instincts have been tamed by his wife, who he loves. However, in some episodes he expresses nostalgia for the times when he was just a simple cowboy. In "Murder in the Middle Pasture" when Sally May is giving Slim a lecture on how he will understand the importance of social events when he is married, Loper mouths the words "no you won't" behind her back. While Loper makes fun of Hank frequently and is often angry at him, he also relies on Hank to help with the cattle herding. In "Every Dog Has His Day" Hank saves Loper from some quicksand, proving his loyalty to his master. He is shown to be stubborn. He often refuses to listen to the advice of Slim Chance, which usually ends with some type of incident occurring which Slim had tried to warn him about.

Little Alfred: Loper and Sally May's older child. Little Alfred (middle name Leroy) likes Hank and often participates in adventures with him. Some of these are harmless, though in "The Case of the Hooking Bull" Alfred deliberately tricks Hank into going into the dryer and then turns the machine on, showing he has a mischievous streak. Most of the story "Lost in the Dark Unchanted Forest" revolves around Hank's search for Alfred when he goes missing in the woods. In this story and a few others Alfred is shown to have the ability to talk to animals, although in later stories he does not appear to have this ability. It is revealed that the older a child gets, the more their ability to understand animals diminishes. Hank is very protective of Alfred and frequently risks his life to protect him, labeling it every cowdog's duty. In fact, he saves Alfreds life several times, such as in "The Black Hooded Hangmans". Alfred first appears in book #2, The Further Adventures of Hank the Cowdog, though he is referred to at that time only as "the baby."

Pete the Barn Cat: Hank's primary antagonist on the ranch. Pete is Sally May's favorite pet and he frequently uses this to his advantage in his petty clashes with Hank. Pete is much more clever than Hank and usually manages to outwit him, although Hank usually perceives the events differently. Many of Hank's adventures are initiated by an embarrassing incident where he has been tricked by Pete. In "The Further Adventures of Hank the Cowdog", Hank's eyes go crossed after staring at a bloody nose he received by attacking a fried egg Pete obtained that was just behind Sally May's garden fence. In "The Curse of the Incredible Priceless Corncob", the entire story revolves around Hank's over-protectiveness towards a corncob Pete has tricked him into believing is worth a fortune. In "The Case of the Missing Cat" Hank eventually loses patience with Pete and tries to strand him on the plains, but has a change of heart and rescues him from the coyotes Rip and Snort. The two then lament the fact that by saving Pete's life Hank and Pete must be friends and stop fighting each other. At the end of the adventure, however, the two return to fighting over scraps, suggesting that they both secretly like their antagonistic relationship. Pete is also referred to as "Pete The Cow Cat" in the book "The Case Of The Perfect Dog", where Pete wanted to replace Hank as top dog. Although Pete usually manages to outwit Hank initially, Hank sometimes gets revenge near the end of the story, such as in "The Case of the Dinosaur Birds." In the "Secret Sleeping Powder Files", Pete becomes lost, and Hank reluctantly helps find him, at the request of Sally May.

Slim Chance: A lazy but loyal cowboy and ranch hand that works for High Loper. It is unclear how long Slim has worked at the ranch, but despite several comments made about wanting to move to a bigger operation, he has never quit.In "Slim's Good-Bye," Slim does leave the ranch due to perceived financial concerns, but changes his mind after Loper tells him that their financial troubles are not as dire as he originally thought. He does most of the work on the ranch that Loper does not want, and occasionally gets forced into babysitting Little Alfred, for whom he has an affinity. Slim lives in a rundown shack two miles from ranch headquarters, and maintains a filthy house, frequently leaving old dishes, clothes, food, and livestock magazines lying around and fostering a chronic rodent problem. He also hates cooking, which results in him maintaining a horrible diet and eating things that would disgust the average reader, like sardine and ketchup sandwiches and boiled turkey necks. Slim loves pranks, including placing a smoke bomb in the town's volunteer fire department truck and tricking Loper into believing there was a fire causing him to start the truck and set it off. He is prone to making poor decisions, usually due to laziness, often with disastrous consequences. He frequently compares himself to Hank in this regard. Often, when Hank gets into trouble, Slim does not stay mad at him, stating that Hank reminds him of himself. Although Slim loves to play pranks on Hank and poke fun at him, it is clear he has an affinity for both him and Drover, frequently asking them to come along with him on odd jobs. Hank saves his life on several occasions, such as in "The Case of the Prowling Bear" and "The Hooking Bull". The first audio-only book, The Homeless Pooch, establishes that Slim is Hank's owner; however, in other books in the series Hank and Drover are said to be Loper's dogs, or even Alfred's. He speaks with a strong southern drawl. He plays a role in almost every book, and appears most frequently of all the human characters.