Kathrena Winterwisp comes from Dave Kosak's "Flintlocke's Guide to Azeroth."

In today's card reveal stream the Hunter Legendary from Kobolds & Catacombs was revealed. Kathrena Winterwisp is a slow card that seeks to push Control Hunter even further. While we don't yet know what the Legendary class weapon will be, the other cards we've seen thus far, Wandering Monster and Crushing Walls, are also supporting cards of the archetype. As with any other significant card in Hearthstone, we couldn't help but wonder the lore behind Kathrena. After doing some investigation over on Wowhead, we've discovered her origins lie in now Game Designer for Hearthstone, Dave Kosak.

In short, Dave Kosak when working for Gamespy he ran a webcomic called Flintlocke's Guide to Azeroth. According to the Wowhead guide it's about "Fargo and Flintlocke, a confused Warrior who wants to be a Hunter and rides a dead ram mount and has annoyed Ironforge in spite of being a dwarf."

Kathrena was a character in this comic before being added to World of Warcraft, presumably after Kosak made the jump to Blizzard.
 

The Alliance version of this follower, Kathrena Winterwisp, closely resembles the character Kathrena from the webcomic Flintlocke's Guide to Azeroth. Her first name, appearance, class and gear all resemble Kathrena's. This character also appears as a questgiver in Darkshore.

I have found a number of other followers based on the main characters from Flintlocke's Guide to Azeroth and Flintlocke vs. the Horde, most of which use the same names as the characters they are based on. 

"Doc" Sweitzer is apparently available to both Horde and Alliance, which is appropriate as he is an Alliance character who somehow joined a Horde guild. The Alliance also has Bloodrose and Kathrena Winterwisp, Fargo Flintlocke, and Lowping. Kathrena also appears as a questgiver in Darkshore, and Fargo Flintlocke plays a major role in some Alliance quests in Twilight Highlands.

The Horde has Cheri, Gravy and Rok'tar. Gravy has also been working at the inn in the Valley of Honor since Cataclysm came out. Like Flintlocke, Rok'tar also has a tribute npc in Twilight Highlands, though the player has much less interaction with him than with Flintlocke. Calder Gray appears multiple times in Cataclysm content and bears a strong resemblance to the unnamed shadow priest in Flintlocke vs. the Horde (who was nicknamed "Bubbles" by the comic's fans).

Both comics were created by Dave "Fargo" Kosak, who now works at Blizzard as the Lead Narrative Designer for World of Warcraft. The comics were hosted on Gamespy, which has since been taken down.
Edit: The comics are no longer only available via Wayback Machine! The comics have been reposted at:

http://flintlocke.thecomicseries.com/archive/

http://flintlockevshorde.thecomicseries.com/

Source

More information can be gleaned from Wowhead's guide Blizzard and Community References in WoW.

Back to TopDave "Fargo" Kosak

Before working at Blizzard, Lead Narrative Designer Dave Kosak worked at Gamespy and wrote the Flintlocke comic series, featuring Fargo and Flintlocke, a confused Warrior who wants to be a Hunter and rides a dead ram mount and has annoyed Ironforge in spite of being a dwarf.

  • Gravy: One of the main characters in Flintlocke vs The Horde, currently serving as a bartender in Orgrimmar.

  • Fargo Flintlocke sends Alliance players to Twilight Highlands, which is an odd choice after he's nuked Stormwind in a previous installment of Flintlocke's Guide to Azeroth.

  • Rok'tar sends Horde players to Twilight Highlands and is the main character of the follow-up series Flintlocke vs. The Horde.

  • Flintlocke has a number of items named after him, such as Flintlocke's Blasthammer which looks like a melee weapon and fits with Flintlocke's combat style.

  • Flintlocke's Woodchucker references his signature "Chuck-Shot" which was made with blasting powder and an angry woodchuck. This enchant makes your ranged weapon periodically spit out a critter.

  • Flintlocke's Chuckshooter: When looting corpses, Flintlocke also had to remember to pick up the Chuck-Shot dislodged in his enemies. It was quite dirty, leading to the flavor text "This weapon has clearly never been cleaned. Ever."

  • Flintlocke's Piloting Pants: References Flintlocke's debatable skills in flying a "diridgerdabler-able... diriger-jib-gibjer-lobbler... BLIMP" which eventually crashes.

  • Commander Lo Ping: This badge vendor is named after Lo Ping, who enjoyed hoarding tons of items.

Many followers that can be recruited from the Inn are references to Flintlocke:

Source

Looking for more Kobolds & Catacombs information? Head on over to our Visual Card Guide for all of the latest information and a look at what's been revealed thus far!