Kharn the Betrayer

When rolling To Hit with Kharn's melee attacks, any unmodified rolls of 1 are not discarded. Instead they automatically hit a friendly model (but not Kharn) locked in the same combat. Randomly determine (for each roll of 1) which model is hit, from those within 6" of Kharn. If there are no viable targets in range, these attacks are discarded.

Kharn and his unit pass their Deny the Witch on a 2+. Force cannot inflict Instant Death on Kharn.

Kharn's melee attacks always hit on a 2+ (even if they would otherwise hit automatically).

A Model with this rule must issue and accept challenges. Where there are multiple models with this rule, the controlling player may decide.
Whenever a model with this rule kills a character, roll a D66 and consult the Chaos Boon chart. This boon remains for the rest of the game.

Units containing one or more models with the Fearless special rule automatically pass Pinning, Fear, Regroup tests and Morale checks, but cannot Go to Ground and cannot choose to fail a Morale check due to the Our Weapons Are Useless rule. If a unit has Gone to Ground and then gains the Fearless special rule, all the effects of Go to Ground are immediately cancelled.

Independent characters can join other units.  They cannot, however, join units that contain vehicles or Monstrous Creatures.  They can join other Independent Characters, though, to form a powerful multi-character unit!  Independent Characters pass Look Out, Sir rolls on a 2+. A unit that contains one or more Independent Characters does not need a double 1 to Regroup if reduced to below 25% of its starting numbres, but instead tests as if it had at least 25% remaining.

Full details in BRB. Rule too long to copy verbatim.

In a turn in which a model with this special rule charges into combat, it adds +1 to its Strength characteristic until the end of the Assault phase. A model that has made a disordered charge that turn receives no benefit from Furious Charge.

Models with this rule have +1 Ld and Hatred (Space Marines)
This Hatred applies for the following books:
Codex: Space Marines
Codex: Dark Angels
Codex: Space Wolves
Codex: Blood Angels
Codex: Grey Knights

Confers Rage and Counter-attack

If a unit contains at least one model with this special rule, and that unit is charged, every model with the Counter-attack special rule in the unit gets +1 Attack until the end of the phase.

If, when charged, the unit was already locked in combat, the Counter-attack special rule has no effect.

In a turn in which a model with this special rule charges into combat, it gains +2 Attacks for charging, rather than +1. A model that has made a disordered charge that turn receives no benefit from Rage.