Sol

Sol, real name unknown, is a member of the Voyager species and recurring ally to the Two Worlds Team. He appears frequently throughout the series.

Character History
Sol claims to have been monitoring Earth for at least 200 years, voicing recollection of a great industrial boom (Industrial Revolution), marred by a world war (World War I). While monitoring Earth 2, Sol's vessel was destroyed and he somewhow passed through the Harker Doorway, critically injured. He is treated by Dr. Amanda Shaw and holds his life in her debt. He is later recalled back to his own galaxy by another Voyager, Antares. (The Voyager)

Sol makes his next appearance around a year later, when Colonel DeLaney is given a routine tour of Two Worlds headquarters by Doctor Harker. Sol and DeLaney initially seem at odds, DeLaney's forceful by-the-books method clashes with Sol's logical approach, though the Colonel later sees Sol as a valuable ally. (Six Degrees of Toleration).

Notable quotes
"My species does not feel pain. When we die, we die"

- to Dr. Amanda Shaw after being told he could have died, The Voyager

"Have we met?"

"Perhaps in another life. Though Dr. Shaw is the first of your race to encounter one of mine"

"Well then, allow me to establish first...well, second contact with your species"

- Colonel DeLaney and Sol meet, The Pact

"Your prejudice is unfounded, and unlogical, colonel"

"What are you!? A godamn Vulcan!?"

- Sol and Colonel Delaney, Endgame

Behind the scenes
Sol is voiced by Brent Spiner, widely known for his role as  Data in  Star Trek: The Next Generation. Sol's fellow Voyager, Antares, is voiced by another Star Trek alum, Rene Auberjonois (Odo is  Deep Space Nine).

When Sol meets Colonel DeLaney, their conversation is a tribute to  Star Trek: First Contact, in which both Brent Spiner and James Cromwell appear.