Rugal Bernstein (Japanese: ルガール・バーンシュタイン, Hepburn: Rugāru Bānshutain) is a character from The King of Fighters series created by SNK. First introduced in The King of Fighters '94, he is a recurring boss in the series, appearing in some titles as an enhanced version called Omega Rugal (オメガ・ルガール, Omega Rugāru). As the host of the tournaments from The King of Fighters '94 and '95, Rugal plans to turn all the competitors from the tournament into stone statues as part of his collection. Despite his death in '95, Rugal is still featured in certain The King of Fighters titles which do not contain a storyline (nicknamed "Dream Matches"). He has also been featured in the Capcom vs. SNK series as a boss character.

Rugal has also appeared in other media related to The King of Fighters franchise, including comic adaptations and The King of Fighters live-action film, and portrayed by British martial arts actor Ray Park. As the first boss character from The King of Fighters, the SNK staff created him to be one of the most difficult characters to defeat. His Omega Rugal form from '95 has been noted by the staff to be their favorite boss to the point they added him in the Dream Match titles.

Publications for video games and other media have provided praise and criticism for Rugal's character.

During development of The King of Fighters '94, several final boss designs were considered, including a masked dominatrix with a spiked whip, a long haired gentleman in a formal suit, and an early sketch of a muscular man wearing a mask and checkerboard sash around his waist. The concept for making Rugal was to make "the biggest, baddest, most evil villain imaginable," due to the planning team's love of villains, and as his character evolved a planned in-game team consisting of series bosses Geese Howard and Wolfgang Krauser was scrapped to further highlight him. The stage you fight him in was meant to reflect his personality, and at one point they considered it to be a giant mecha modeled after his appearance, before switching to an aircraft carrier. Rugal has been described by developers as "He's the only character who truly represents the ultimate KOF boss" and has become the boss character with the biggest number of appearances in The King of Fighters series, becoming a favorite character among both the developers and series artist Falcoon. The character's popularity has continued even to his appearance in The King of Fighters XV, with artist Tomohiro Nakata surprised by how acclaimed the decision to include Rugal was. Due to his multiple "deaths" in the series, developers jokingly added the hobby "resurrection" to his official profile.

Standing 1.97 m (6 ft 5 in) tall, Rugal is a tall, blonde and athletic man with a thin mustache and his right eye missing. His normal outfit consists of a red formal tailcoat suit with black accents, fingerless gloves, a black cummerbund and ribbon tie, and a white shirt underneath. This outfit has been used for most of his casual appearances, including crossover titles such as Capcom vs. SNK: Millennium Fight 2000 and its sequel. In The King of Fighters '94, when he is defeated the first time he will toss away most of his upper clothes, now wearing a black sleeveless undershirt with his suspenders dangling loose while, and fighting more seriously.

In The King of Fighters '95, though other options were considered Rugal returned as the game's final boss with a modified design. Many ideas were considered for this version, including having him fight shirtless with a tattoo of a leopard covering his left arm and pectoral, a design with armor embedded into his flesh, and another featuring heavy cybernetic implants, with goggles covering his eyes and wires extending from his arms into his chest. A more outlandish design, called "Rugal Infinity", would have featured his body merged with Geese and Krauser, appearing as a six armed naked man with the other two men's faces sticking out of the sides of his head, akin to depictions of the god Ashura. Dubbing him "Omega Rugal", they ultimately settled on an appearance similar to his King of Fighters '94 counterpart, but with his upper body having burst from his clothing, wild white hair, cybernetic prosthetics replacing his right hand and eye, and the Greek letter "Ω" tattooed on his back. Director Masanori Kuwasashi was in charge of the making of this version of the character, aiming to give loose ends with the Orochi demon explored in the series' first story. Omega Rugal later returned in King of Fighters '98, his design changed with the developers focusing on using his secondary 'serious' appearance in '94 as a base, while retaining the cybernetic red eye. This served as Omega Rugal's look from that game onwards with minimal modifications and additions, such as a costume variant adding a red longcoat and armored shoulderpads in XV as an unlockable reward for defeating him as a boss.

Rugal was introduced in the 1994 game The King of Fighters '94, as a megalomaniac arms dealer inviting fighters from all over the world to fight in his martial arts tournament, seeking worthy opponents and turning those he defeats into stone statues for his throne room. Protagonist Kyo Kusanagi and his teammates make it to the finals, where he finds his father Saisyu has already fought against Rugal and suffered a mortal blow. Angered, Kyo defeats him, but Rugal activates a self destruct sequence in an attempt to kill him. In The King of Fighters '95, Rugal organizes a new King of Fighters tournament to take revenge on Kyo. To this end, Rugal revives and brainwashes Kyo's father to kill him. After Saisyu is knocked unconscious, Rugal fights them in an enhanced form named Omega Rugal. Once defeated, his body is unable to handle the stress, and as his body disintegrates declares he will return. Omega Rugal later returns in "dream match" King of Fighters titles, non-canon entries in the series, serving as the final boss for both The King of Fighters '98 and The King of Fighters 2002, and appearing as an optional boss in their subsequent remakes. In The King of Fighters 2000, Rugal appears as a non-playable assistant character (dubbed a "striker") to Kula Diamond. After the events of The King of Fighters XIV, Rugal is revived and returns as a playable character and optional boss in downloadable content for King of Fighters XV.

In other fighting games, Rugal appears as the final boss of King of Fighters R-2 for the NeoGeo Pocket Color, a chibi parody of King of Fighters '98 in which he is creating clones of other fighters, and upon defeat self-destructs his aircraft carrier with a cartoon bomb. He also appeared in VersusTCG, a physical trading card game based on the first game. In mobile games, he appears as a boss in a King of Fighters themed event for Puzzle & Dragons.