Ktarians

Player Race: Yes
Relation to UFP: Last known to be neutral.

ACTDNoteworthy:
- they've tried taking over the Federation, however there is still friendly contact with them as evidenced by the Wildmans.
- They could definitely be a member of the Federation, but there is still no 'solid' evidence to prove that...  just because some of them live on earth could just mean they are very friendly with the Federation.

Description
Humanoids characterized by thei enlarged frontal skull bones and feline eyes.  Native to planet Ktaria VII.  Although politically nonaligned, in 2368 the Ktarians devised a plan they referred to as the expansion, intended to gain control of the Federation Starfleet, and eventually of the Federation itself.  They distributed a psychotropically addicative Ktarian game to members of the Enterprise-D crew, planning to use the crew as tools in their planned expansion (The Game -TNG).  Ensign Samantha Wildman's husband, Greskrendtregk, was Ktarian (Dreadnought -VGR).  Ktarians have scales on some parts of their body and have cranial ridges running from the center of their forehead over to the back of their head (Deadlock -VGR).
Star Trek: The Encyclopedia (1999 edition).

Civilization in the Alpha Quadrant.  Ktarian children develop much faster than human children.  Naomi Wildman was half Ktarian (Mortal Coil -VGR).  Many Ktarians lived on earth in the 24th century (Hope and Fear -VGR).
Star Trek: The Encyclopedia (1999 edition) -Supplement