Seelos

Seelos was a member of the Dai-ai species in the 24th century, from the planet Naia VII.

In a parallel universe in 2368, Seelos greeted Commander William Riker, Lieutenant Commander Data and Lieutenant Worf of the USS Enterprise-D when they visited the Starfleet Corps of Engineers mining operation on Naia VII, after Captain Ochoa introduced them.

Later, following a flooded mine disaster, Seelos explained his people's unwillingness to aid the rescue efforts to Captain Jean-Luc Picard.

Picard later returned, seeking a large supply of the planet's gold to combat a Cyberman threat. As gold was one of the embargoed materials in the Federation's agreement with the Dai-ai, Seelos surfaced to negotiate. Though he was initially unwilling to give up the gold, the Eleventh Doctor recognised that the Dai-ai feared the size of the Federation and convinced Seelos that helping to stop the Cybermen would grant the Dai-ai enormous bargaining power and the gratitude of the galaxy. (COMIC: Assimilation²)

Behind the scenes
While Assimilation² established a temporary merging of the Federation universe and the Doctor's universe, Seelos was firmly established as a denizen of the former when his homeworld returned in .