Planetouched

Planetouched is a general category of races that shows up in Dungeons & Dragons and Pathfinder. Semi-official, it is a general term for races who have mortal ancestors, but who are marked by the outer planes. Usually, this specifically means having an ancestor who somehow bred with an extraplanar being, but it can also manifest as a result of arcane pacts, exposure to planar energies in-utero, wizardly meddling, blessings/curses (particularly by planar beings) and all other sorts of non-sexual stuff.

Tieflings

The original and, in the eyes of many, the best Planetouched, tieflings started it all when they appeared way back in the Planescape Campaign setting. They are the descendants of mortals and fiends - the denizens of the Lower Planes.

The general tiefling is expected to be of human ancestry; demihuman tieflings consist of the Fey'ri (Elf) and Tannaruk (Orc) from Monsters of Faerun, the Maeluth (dwarf/devil) and whispling (halfling/demon) of Fiend Folio, and the Worghest (goblin/barghest) of Dragon Magazine #350.

For more details, see their page: Tiefling.

Aasimar

The counterpart to tieflings, aasimar trace their lineage to the Upper Planes and its resident celestials.

There are far fewer aasimar/demihuman crosses, with the only named example being the Celadrin (elf/eladrin) of Dragon Magazine #350.

For more details, see their page: Aasimar.

Genasi

Seeing the pattern here yet? These are your basic Elemental Planetouched, with powers relating to earth, air, water or fire.

For subraces, we got two demihuman-specific crosses (the Dwarf/Azer hybrids called "Azerbloods", and the Halfing/Genie hybrids called "D'hin'ni", both from Dragon Magazine #350), and an assortment of alternate elemental affinities. Dragon Magazine #297 gives us Paraelemental Genasi (Dust, Ice, Magma, Ooze, Smoke and Steam), 4th edition had Athasian Genasi of Sand, Silt, Sun and Magma, whilst a Ravenloft fan-splat called Quoth the Raven #7 has Dread Genasi (Grave, Mist, Blood and Pyre).

Yet again, check their page out here: Genasi.

Axani

Hailing from Dragon Magazine #297, the Axani are the inevitable "Axiomatic Planetouched", to contrast the Upper, Lower and Elemental Planetouched we already got. They're associated with all the Lawful Neutral planars, and to a lesser extent the ultra-lawful Upper and Lower Planes. They're extremely organized, disciplined and regimented, as you'd expect of someone with pure Law in their bloodline.

Cansin

The Axani's counterparts, the Cansin are the spawn of pure chaos, serving the role of "Anarchic Planetouched".

Mechantrix

No, not some sort of dominatrix warforged monstergirl. These are planetouched who (somehow) display heritage connecting them to the mechanical outsiders of Mechanus -- the Modrons and the Inevitables. They hail from the Fiend Folio.

Shyft

The ghost-like shyft, documented in the Fiend Folio, owe their lineage to the Ethereal Plane. There's not a lot else to say about them.They hail from the Fiend Folio.

Chaond

Coming from the Monster Manual 2 in 3.5, the Chaond are basically the official equivalent to the Cansin, although they are demonstratably tied to Slaadi rather than any generically chaotic outsider.

Zenythri

The Chaond's lawful counterparts.