In many video games, an older male character acts as a source of wisdom and protection for the other characters. Oftentimes, even though he is called an old man and may 'act' like one, this character is usually in their 30s to 40s, putting him in "father figure" territory.
Characters who can actually be considered grandpas aren't as common in video games, but there are a few. Sometimes these grandpas are masters of their field and act as instructors to the younger generation. Sometimes they're used as comedic figures and other times they're just normal grandpas.
10 Cranky Kong
The apparent patriarch of the Donkey Kong family, Cranky Kong is the grandfather of the modern Donkey Kong from Donkey Kong Kingdom. Cranky Kong is the original Donkey Kong from the retro arcade games.
In the Donkey Kong Kingdom, he usually acts as a source of information for players and sometimes acts as a shop owner. He becomes a playable character in Donkey Kong Country: Tropical Freeze. He is a bitter and grouchy character that fusses at his grandsons but deep down he cares about his family.
9 Toadsworth
Toadsworth is the mustached elderly Toad that has been Princess Peach's aide for a long time. He's first introduced in Super Mario Sunshine, and he makes several appearances and cameos in other games. The Mario Baseball spinoff series is the first time he is a playable character.
He's the kindly old butler type who is very loyal to Princess Peach and becomes frantic whenever she is kidnaped or in danger. It isn't exactly clear if he has any sort of familiar relationship with Peach, but he had a hand in raising her and cares deeply for her. His name includes the word for 'grandpa' in a few different languages when it gets localized.
8 Professor Oak
Professor Oak is the first Pokemon professor introduced in the series. And in the Generation One Pokemon games, he is the person that gives the player character their first Pokemon. He is also the grandfather of the player's rival, Blue.
He's the most well-known of the Pokemon professors and has become friends with many of them. In the Generation Four games, he's the one that gives the player the National Pokedex. He's a kindly older man who focuses on the relationships between Pokemon and humans.
7 Heihachi Mishima
Not all grandpas are kindly old men that want to protect their grandchildren, and Heihachi Mishima is a prime example of that type of grandpa. Heihachi is one of the main antagonists in the Tekken series, and he is the father of Kazuya Mishima (another main antagonist in the series) and the grandfather of Jin Kazama, the main protagonist of the series.
He's a cruel and power-hungry man that will do anything to get what he wants, including using his son and grandson in experimentation. He's disliked by all his family members and doesn't have any particular fondness for them. Despite all that, he is capable of caring about something as he has a bear named Kuma who is his friend and bodyguard.
6 Sebastian
Sebastian is another grandpa from Tekken, who is much kinder than Heihachi. He is the butler of the De Rochefort family, and he is in charge of overseeing Lili.
He is devoted to her and also cares deeply about her. Sebastian makes an appearance in her endings in both Tekken 5 and Tekken 6. Players can finally get their hands on him as an actual character that can be played in Tekken Tag Tournament 2 and his fighting style takes after Lili's with a few minor differences.
5 The Great Kung Lao
Mortal Kombat has many characters that can be considered ancient beings despite having youthful appearances, though most of them wouldn't be considered grandparents. One character that could be considered a grandpa, though he'd technically be a great-great-great grandpa. The Great Kung Lao is an ancestor of modern-day Kung Lao, which fans of the series will be more familiar with.
A member of the Order of the Light while representing Earthrealm, he was the first of his kind and became the Grand Champion after defeating Shang Tsung. In Mortal Kombat 11 he can be summoned as an assist for Kung Lao and in MK 11: Aftermath he makes an appearance in the ending of Fire God Lui Kang, where the next champion is chosen.
4 Hala
Hala is another grandpa from the Pokemon series. He's also the grandfather of the player's character's rival, just as Professor Oak is in the Generation One games. Instead of a Pokemon professor, Hala is the kahuna of Melemele Island in Pokemon Sun and Moon.
He is a fighting-type Pokemon specialist and a member of the Alola Elite Four. In Sun and Moon, he's the one that gives the player their starter Pokemon, though it was changed to Professor Kukui in Ultra Sun and Ultra Moon.
3 Gen Fu
Gen Fu is one of the characters in the Dead or Alive series. He's a secondhand bookstore owner who is also a skilled master in the Xin Yi Liu He Quan martial arts style. Gen Fu is possibly one of the best grandpas in video games, as his only reason for joining the Dead or Alive Tournament was to use the prize money to help pay for his granddaughter's medical care when she was sick.
He only competes in the first three tournaments as by the fourth one his granddaughter has fully recovered. However, since the third tournament, he took on Eliot as his apprentice and trains him in his martial arts style.
2 Grandpa
Only known as "Grandpa", players are introduced to their character's grandfather in a letter that they read at the introduction to Stardew Valley. It can be assumed that the player character was somewhat close to Grandpa as he wrote them and gifted them the farmhouse. At the start of the third year, Grandpa's Ghost will come and evaluate their success in the game, based on their player level, how much money they've earned, their achievements, their friendships, and other things.
Grandpa was the focus of the Stardew Valley modding community for a time as modders changed the introduction scene. Changes vary from giving Grandpa a much better bed to turning him into a bed.
1 Goku
When Gohan gets older he marries Videl, and they have a daughter named Pan, making Goku a grandpa. Goku is in every single Dragon Ball game in the franchise, and he is either a playable character, an assist, or a teacher depending on the game.
In Dragon Ball Fusions several versions of Goku appear throughout the game, including a child version of himself from the Dragon Ball era. When he meets his granddaughter, she mistakes him for his Dragon Ball GT child version, at first.