Captain Tycho, The Fallen Star

Can only join a Death Company Squad

A unit composed entirely of models with this special rule can re-roll one or more of the dice when determining Run moves and charge ranges (such as a single D6 from a charge range roll, for example).

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.

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.

When a model with this special rule suffers an unsaved Wound, it can make a special Feel No Pain roll to avoid being wounded (this is not a saving throw and so can be used against attacks that state that 'no saves of any kind are allowed', for example those inflicted by Perils of the Warp).

Feel No Pain saves may not be taken against Destroyer attacks or against unsaved Wounds that have the Instant Death special rule.

Roll a D6 each time an unsaved Wound is suffered. On a 4 or less, you must take the Wound as normal. On a 5+, the unsaved  Wound is discounted - treat it as having been saved.

If a unit has the Feel No Pain special rule with a number in brackets afterwards -Feel No Pain (6+), for example - then the number in brackets is the D6 result needed to discount the Wound.

Relentless models can shoot with Heavy, Salvo or Ordnance weapons, counting as stationary, even if they moved in the previous Movement phase. They are also allowed to charge in the same turn they fire Heavy, Ordnance, Rapid Fire or Salvo weapons.

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.

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.