Half-Clan

Half-Clan cats are cats who have mixed heritage, their parents coming from different Clans.

Description
Taking a mate from another Clan is implicitly forbidden by the first rule of the Warrior Code. Such pairings are considered a sign of disloyalty.

Kits born as a result of such forbidden relationship are usually taken in by the Clan of the mother. They are considered half-Clan and are looked down upon by pure-blood Clan cats as their commitment to their foster Clan can be questioned. Sometimes they are in danger, like when Tigerstar took over RiverClan and planned to kill off all cats with mixed heritage.

Cats who have one parent from outside the Clans (a rogue, a kittypet) can also be considered half-Clan; but usually are not suspected with disloyalty, as they do not have two different Clans to feel loyalty for. (GraystripeXSilverstream)

Cats with parents from different Clans
At their conception or birth, their parents were members of different Clans:
 * Mistyfoot and Stonefur: ThunderClan and RiverClan descent
 * Feathertail and Stormfur: ThunderClan and RiverClan descent
 * Jayfeather, Lionblaze and Hollyleaf: ThunderClan and WindClan descent
 * Windflight: ThunderClan and WindClan descent

Cats with a non-Clan parent
At their conception or birth, one of their parents was a Clan cat, and the other not:
 * Hawkfrost and Mothwing: ShadowClan and rogue descent (by birth), ThunderClan and kittypet descent (by blood)

Cats with blood of different Clans
Their parents were born in different Clans (even if later they were in the same Clan):
 * All cats with parents from different Clans (see above) and their descendants
 * Pinestar and descendants: ThunderClan and SkyClan
 * Tigerheart, Flametail and Dawnpelt: ThunderClan and ShadowClan

Cats with a non-Clanborn parent
A parent was not Clanborn (even if he or she joined a Clan later):
 * All cats with a non-Clan parent (see above) and their descendants
 * Squirrelflight, Leafpool and descendants: ThunderClan and kittypet
 * Toadstep and Rosepetal: ThunderClan and kittypet
 * Briarlight, Blossomfall and Bumbleflight: ThunderClan and kittypet

Cats changing Clans
Although not half-Clan by birth, their loyalty to their foster Clan can be questioned in the same way as that of a half-Clan cat, as they broke the first rule of the Warrior Code and are attached to two different Clans:
 * Graystripe: a ThunderClan cat who joined RiverClan, and later rejoined ThunderClan
 * Yellowfang: a ShadowClan cat who joined ThunderClan
 * Tigerstar and Tawnypelt: ThunderClan cats who joined ShadowClan
 * Stormfur: a RiverClan cat who joined the Tribe, rejoined RiverClan, joined ThunderClan, then rejoined the Tribe