Lucas (Japanese: コウキ Kōki) is the male Pokémon player in Pokémon Diamond, Pokémon Pearl, and Pokémon Platinum. His female counterpart is Dawn.
In Diamond and Pearl, Lucas wears a white undershirt with a black vest over it, a red scarf, blue baggy jeans, with red and grey shoes. In Platinum, he now wears an outfit more suitable for the weather in the game, which is a dark red full-sleeved shirt with a dark blue and black jacket over it, a white scarf wrapped around his neck, denim black pants with dark gray and white running shoes, and a dark red hat with a white and black semi Poké Ball on the back.
Lucas' Diamond and Pearl outfit looks similar to Ash's regular Sinnoh outfit.
In the anime, Lucas' white shirt is pale sky-blue, and his black vest is dark-blue. Also, his blue jeans are dark-teal.
In the games
As the Player
He lives in Twinleaf Town with his mother, Johanna, and his best friend and rival, Barry. He recieves his first Pokemon from Professor Rowan's briefcase and begins his journey across Sinnoh. In Diamond and Pearl, he recieves his first Pokemon in Lake Verity after he and Barry are attacked by wild Starly. In Platinum, recieves his first Pokemon in Route 201 instead of Lake Verity and he battles Barry after Prof. Rowan goes back to Sandgem Town with his assistant, Dawn. He also meets Looker, an officer of the International Police who looks after Team Galactic. In Diamond, Pearl and Platinum, he has to stop Team Galactic and Cyrus from destroying the entire universe.
When he is not chosen as the player, he is Professor Rowan's assistant. He lives in Sandgem Town with his father, who is also one of Professor Rowan's assistants, his little sister and his grandfather. He shows Dawn, the player, the Pokemon Center and the PokeMart and teaches her how to catch a Pokemon.
Lucas, when not chosen by the player, always seems to have possession to Professor Rowan. When Dawn, the player character, comes to Sandgem Town for the first time, he greets her and shows her the lab. He makes two appearances in Jubilife City, another appearance in Route 207, and yet another appearance in Canalave City, when he is sitting near Professor Rowan, while Barry and the player character sit in front of them. In Diamond & Pearl, he also appears at Spear Pillar and sees the player character defeating Dialga or Palkia.
In the anime
Lucas has a counterpart who shares his name. He makes a cameo appearance at the beginning of Giratina and the Sky Warrior, in a battle against Brendan. His only known Pokemon is his Magmortar, that battled against Brendan's Rhyperior.
In the manga
Lucas has a counterpart named Diamond, who is one of the deuteragonists of the Diamond and Pearl arc, the other one being Pearl (Barry's counterpart). Diamond lives in Twinleaf Town with his mother Johanna and his best friend, Pearl. When the two meets a girl named Platinum (Dawn's counterpart), she mistakes them for her bodyguards, as they matched the description of one of them having a red scarf and the other one having a green scarf.
- Lucas's Platinum outfit seems to be the inspiration for the coats that Ash and Brock wore when they visited Snowpoint City.