Humans are the most numerous and dominant species, with apparently millions of major and minor colonies galaxywide.
Humans
In the Star Wars universe, Humans were one of the first species to develop the hyperdrive, Corellians the first to do so. By this time humans were already present on a few scattered worlds throughout the galaxy, which implies that they had a slower means of interstellar transport for a while earlier.
Star Wars Humans are mostly identical to earth humans. The home planet of humanity has never been identified, although it is most likely that humans first evolved on Coruscant, which later became the center of galactic government.
Most Star Wars humans live on predominantly human worlds, although many populations live alongside aliens on other worlds, or together with several other species - something which is most common either on the cosmopolitian worlds at the core, or on the frontier at the outer rim of the galaxy, such as on Tatooine.
Human worlds include Corellia and Naboo.
Some Human characters are Anakin and Luke Skywalker, Padmé Amidala, Boba Fett, Han Solo, and Lando Calrissian.
Near-humans
Several species in the Star Wars universe appear to be very closely related to humans, as they share many physical traits. These are described as being 'Near Human' and are said to have descended from humans that evolved along distinct lines on other worlds.
Chiss
The Chiss, a race that dwells in the Unknown Regions, are a humanoid people that have pale blue skin, black hair, and red reflective or fluorescent eyes. In all other aspects they are normal humans: they bleed red blood, and the cloning tanks used to clone human stormtroopers also worked on Chiss physiology.
Grand Admiral Thrawn is the most famous Chiss.
Sith
The Sith 'race' are an interesting case, in that their ancestry includes a non-human alien group that were genetically tampered with by a group of human Dark Jedi that settled on their homeworld, to escape from the Republic. The intermixing of human and Sith bloodlines, through the use of what became known as Sith Alchemy, created the Sith, with their characteristic red skin and long tentacle 'beards'. Due to their history of association with Dark Side Force users, the word 'Sith' went on to be used by many dark side organizations not connected with the original Sith species.
Zeltron
Zeltron are near humans and bear a similar appearance, save for their pink skins, which may or may not be a result of their sun's highly radiatioactive rays. They are a highly sexual race, and are famous for their many sculptures and paintings on the subject. They also have made great strides in the field of holograms and are responsible for the ones used at Hologram Fun World.
Others
Other near-human races mentioned in various books and comics include the Theelin, the Arkanian, the Chev, the Omwati and the Ubese. All these are mostly human in appearance, but have a few distinct defining characteristics.
The Duros are the only other species in the Star Wars galaxy known to have a genetically distinct separate sub-species that arose from natural evolution, (the Neimoidians) - although the similarity between the Quermians and Xexto is said by some to indicate that they are also related.