When I type in WHO, why is there a (PK) in front of my name?

This is taken directly from a helpfile within the game. If you typed "help PK" you would have found this.

PK range is the group of other characters (players, not NPCs) that you can
fight. If a character is not within your pk, you cannot initiate battle
with them, and will instead get a message saying something like, 'The Gods
protect <name>.' People within your pk range will be designated with a (PK)
before their name.

PK ranges begin at level 11. Below this level, the only person with the (PK)
flag before their name will be you. (You can always cause you own death,
after all.)

The following are some examples of when the (PK) flag is visible.

By typing 'who pk':

< Arial > (PK) Laoshi the Knight
* Gnome * (PK) Dysvarden the Conjurer //the *'s designate your character
< Storm > (PK) Onotrem the Gladiator
< Arial > (PK) Torado the Trainee
< Duerg > (PK) Rynyn the Stealer
< Storm > (PK) Seedrin the Inquisitor
< Human > (PK) Ralio the Demon Slayer
< Gnome > (PK) Laabspa the Student of Lightning
< Elf > (PK) Bercksoyer the Balladeer
< Elf > (PK) Erehdyl the Ranger Initiate

By typing 'where':

People near you:
(PK) Rynyn A Woodland Trail
Lethiet The Emerald Forest
(PK) Dreaxerus A Woodland Trail
(PK) Loxizer A Woodland Trail


By typing 'who':

< Svirf > Gilhaden the Fencer
< Duerg > Dwoggurd the Weaponsmaster
< Elf > Crimthann the Student of Evocation
< Duerg > Glarek the Zealot
< Storm > Benkei the Swordpupil
< Lich > Dullameh the Enlightened Wanderer, High Chancellor of Necromancy
< Elf > Gorach the Master of Harmony
< Human > (PK) Santerfias the Lieutenant
< Storm > Tulekennan the Enlightened
< Dwarf > Thywar the Champion
< Human > Uizare the Changeling
< Dwarf > Vastagon the Champion, Magistrate of Galadon
< Arial > (PK) Torado the Trainee
< Dwarf > Wasarbre Obaneth, Knight Crusader, Hand of the Icy Drake, First Talon

See also: PLAYERKILL TIPS EXPERIENCE DISTENTION