From Wookieepedia, the Star Wars wiki.

Joiner was the name given to the non-Killiks who were absorbed into the Killik hive mind. This was caused by being exposed to the large amounts of pheromones that the Killiks secreted that changed a person's brain structure, though this could be reversed with proper medical treatment, as was the case with Jaina Solo and Zekk.

It was not revealed whether the Joiners were unjoined from the Killiks after the Colony was put into disarray after the death of Lomi Plo and UnuThul's capture by the Galactic Alliance. At least some of them, such as Jaina Solo and Zekk, were unjoined.

Known Joiners

• Daer'ey'ath
• Beda Ies
• Eremay Ies
• Lomi Plo
• Alema Rar
• Jaina Solo
• Raynar Thul (UnuThul)
• Tito
• Welk
• Yugi
• Zekk

Partial Joiners

• Lowbacca
• Tekli
• Tesar Sebatyne
• Ben Skywalker
• Tahiri Veila

People who were resistant to the Joining process

• Luke Skywalker
• Han Solo
• Jacen Solo
• Tenel Ka

Races whose members became Joiners

• Aqualish
• Chiss
• Defel
• Duros
• Falleen
• Fefze
• Flakax
• Geonosian
• Human
• Ishi Tib
• Kamarian
• Neimoidian
• S'krrr
• Snutib
• Twi'lek
• Verpine
• Vratix
• Yam'rii (otherwise known as Huk)

Appearances

• Dark Nest I: The Joiner King (First appearance)
• Dark Nest II: The Unseen Queen
• Dark Nest III: The Swarm War
• Bloodlines (Mentioned only)
• Tempest
• Exile
• Sacrifice
• Inferno
• Fury
• Invincible (Mentioned only)

Sources

• The New Essential Chronology