He was voiced by the late Bill Scott in the original series, Ty Burrell (who also played Phil Dunphy, Bailey and Leonard Samson) in the film, and Chris Parnell (who also played Jerry Smith) in the reboot series.
Peabody's Improbable History
Peabody was a puppy when he made his first genius accomplishments, and was known as the "Puppy Prodigy". At the age of three, he got his degree at Harvard (Wagna-Cum-Laude). Then he did some brief work for the foreign service (he speaks eight languages, including English, fluently). Next, he worked on some research projects for the Government, and also dabbled in the stock market, where he became the "Woof of Wall Street". Despite his success, Peabody felt something was missing in his life, and after seeing a movie poster of a boy and a dog together, he decided to adopt a boy for a pet.
Peabody searched high and low for a boy, but could not find one that met his high standards. While walking by an alley, he saw a young boy getting beat up by a group of bullies. After scaring the bullies away, the boy introduced himself as Sherman. Peabody took Sherman home to the orphanage he lived in, but after seeing how cruel the owner was, he made up his mind to adopt Sherman himself.
After submitting references (and getting old friends, one being the President, to write letters), being investigated, and a court hearing, it was settled that Peabody's background was "unimpeachable" and he was finally able to adopt Sherman, who was allowed to move into Peabody's luxury rooftop apartment in New York City. Peabody told Sherman that he was now his owner, not his father and told Sherman to call him "Mr. Peabody".
Peabody soon realized how difficult it was to raise a boy in an apartment, seeing that boys need running room, and so, as a birthday gift for Sherman, he invented a time machine, known as the WABAC. He and Sherman then go back in time to see a Roman speaking in Latin; Peabody then adds a translator circuit to the machine so that everyone seems to speak English and see the Roman again, finding out he is a used chariot salesman. Their next trip is to see Ben Franklin flying his kite, but they find out they cannot interact with the past, so Peabody makes some more adjustments, turning the WABAC from time machine into a "should have been machine" which results in the past they visit being totally cockeyed and now they must save the timeline and rewrite history.
Mr. Peabody & Sherman (2014)
In the CGI film, Peabody appears as the main protagonist of this film. He was different from other dogs, even as a pup, being incredibly smart, and more interested in intellectual pursuits than the usual tricks of regular dogs, like playing fetch, which he called an "exercise in futility". As a result of his oddness, no kids wanted to adopt him, leaving him lonely. Without a human family, Peabody devoted himself to the pursuit of knowledge, culture, and athletics, and became active in many fields. He went on to receive a degree at Harvard (Vale-dog-torian), and devoted his life to helping mankind. He established Peabody Industries, where he pioneered new techniques in alternative energy, solved geo-political conflicts around the globe, and in his spare time, he invented the fist-bump, planking, tear-away pants, autotune, the backside ollie, and Zumba.
One rainy day, as he was walking down the street, he heard crying from a nearby alley, and investigated, discovering an infant abandoned in a cardboard box, with only a blanket, and a paper with the name "Sherman" pinned to it.
Remembering his own childhood, and wanting to give the boy something he never had as a pup, a home and family, Peabody decided to adopt Sherman.
After adopting Sherman, Peabody vowed to be the best father he could be, and to prepare his son for all the wonders of the world, present and past. And so, Sherman inspired the greatest invention of Peabody's life, a time machine known as the WABAC. Using the WABAC, Peabody lovingly tutors him from a young age, and in this enriching spirit, life for the dog and his son proves to be a series of wild adventures throughout time.
Years go by, and Peabody decided it was time for Sherman to go to school with regular children. After reluctantly saying goodbye to Sherman, Peabody gives Sherman a dog whistle to remember him.
Later that afternoon, Peabody is called to the office of Principal Purdy, and finds out that Sherman was tormented by classmate Penny Peterson until he was finally provoked into biting her. Ms. Grunion, an evil Children's Services agent, arrives and informs Mr. Peabody that she will reclaim Sherman if an upcoming inspection of his home makes her deem it unfit for the boy.
Peabody invites the Petersons over to resolve the conflict. While Peabody charms Penny's parents Paul and Patty, Sherman is forced to entertain the hostile Penny. Eventually he is forced to disobey Peabody and shows her the WABAC to impress her which leads to them joyriding in it. Sherman returns moments later in the present to tell Peabody that Penny is in Ancient Egypt and refuses to leave her engagement to Pharaoh Tutankhamun. When they travel there to retrieve her, they explain to Penny that she will be killed upon Tut's young death, but she is dragged to the wedding while the duo are imprisoned after saying they will stop the ceremony. They escape and impersonate the god Anubis long enough to call off the wedding and return to the WABAC.
With the WABAC being low on energy, the trio stop in Renaissance Florence to seek the aid of Leonardo da Vinci to recharge it. While the geniuses arrange the machinery, Sherman and Penny find themselves growing closer as they try Leonardo's flying machine without permission. Angered at Sherman's disobedience, the following trip's tense atmosphere grows much worse when the WABAC is endangered by a black hole, while Sherman is upset that Mr. Peabody didn't tell him that he is at risk of being taken away by Children's Services.
As a result, the WABAC crash lands in the Trojan War, where Sherman runs away to join the army of King Agamemnon. When Mr. Peabody and Penny come to retrieve him, they are swept into the final sacking of Troy as the Trojan Horse rolls out of control with Penny inside. Eventually, the Trojan Horse is destroyed and Peabody is apparently killed in the wreckage.
Desperate to save his father, Sherman and Penny return to the present a few minutes before Sherman returned the first time to get Peabody to remedy the situation. Unfortunately, they are too late to leave before that event occurs followed by the arrival of the original Peabody (who had survived and returned after constructing a primitive WABAC) and Ms. Grunion herself. Now confronted with two Shermans and Peabody unable to explain the bizarre situation adequately, Ms. Grunion summarily declares the home unfit and seizes both Shermans despite Penny's protests that she was at fault. This disrupts the time-space continuum when the copies touch each other and both Mr. Peabodys and Shermans merge. Now with her suspicions confirmed, Ms. Grunion drags away Sherman again and Peabody, enraged at the sight of her hurting his son, momentarily reverts to instinct and bites her.
Now with the pretext to call Animal Control to have Peabody put down as a dangerous animal, Mr. Peabody and Sherman flee in the WABAC. However, a time vortex appears and various historical figures and objects are pulled to the present causing the WABAC to crash and Mr. Peabody is about to be taken away. At this, Sherman protests saying this is all his fault and declaring that he would rather be a dog to be a person as good as Peabody. Moved by this, every historical figure concurs along with Penny and her parents and US Presidents George Washington, Abraham Lincoln, and Bill Clinton declare their support for Peabody's legal custody of Sherman.
Finally, to stop the vortex, Sherman suggests that they use the WABAC to go to the future by a few minutes to undo the damage. With Sherman piloting and Mr. Peabody handling the computations, they are successful with all the historical things returned to their proper times, while the smitten Agamemnon forcibly takes along Ms. Grunion as well, the latter swearing revenge on Peabody.
At the end, satisfied that the space-time continuum has become contaminated with anachronisms, Mr. Peabody and Sherman are closer than ever in a happy life with Penny as a close friend.
The Mr. Peabody & Sherman Show
In this series, he hosts a late night talk show with Sherman. Peabody usually tries to make every show as perfect as can be, but he keeps getting into all kinds of messes with his crazy neighbors and people who cause all of his shows to go haywire.
He also hosts a segment on the series called "Time Travel" where he tells the stories of his and Sherman's time travel adventures.