Terra Prime is an antagonistic group of xenophobic extremists that was introduced in the Star Trek: Enterprise episode "Terra Prime'"
Terra Prime was an organization led by John Frederick Paxton, so the group was initially headquarted on Earth's moon. Founded some time before 2151, many Terra Prime members ascribed to Colonel Phillip Green's views on genetic purity, and saw the introduction of alien races as a threat to humanity.
When the Enterprise was lanunched in 2151 Terra Prime was a small and insignificant organization. Terra Prime complained about the launch of the first NX class starship, but few paid them any heed. United EarthStarfleet officer Malcolm Reed would later recall hearing about their protests at the time but not giving it much thought.
Prior to the Xindi attack on Earth in early 2153, membership in Terra Prime had been steadily decreasing. However the Xindi's actions brought about a resurgence of the organization to the point that highly ranked officials in the UE government became concerned about them.
In 2155, Terra Prime created a binary clone from the genetic material of Charles Tucker and T'Pol. Terra Prime intended to use this infant female clone as a propaganda tool to convince the masses that humanity would go extinct if aliens were not made to leave the solar system. Paxton then relocated Terra Prime's headquarters to Mars, and then hijacked the Veteron Array - which was an extremely powerful device used to divert comets to be used in the terraforming of Mars. Paxton threatened to use the array to destroy Starfleet Headquarters if every alien in the solar system did not leave the system.
The crew of the Enterprise was able to prevent Terra Prime from carrying out their terrorist attack. In the aftermath of the attack Paxton and his followers were taken in to custody. Paxton died in prison a couple years later. The clone - who Trip and T'Pol named Elizabeth T'Les Tucker - died a few days after being rescued due to the faulty technique Terra Prime used to create her.
Terra Prime left the various alien representatives gathered on Earth feeling uneasy about humanity. However, a rousing speech by Archer convinced them to go ahead with creating the Coalition of Planets.
Ultimately, Terra Prime failed in its goal to isolate humanity. Earth would continue to participate in the interstellar community, and would go on to become a founding member of the United Federation of Planets.