|"Parents":|| Dr. Noonien Soong|
|"Grandfather":||Dr. Ira Graves|
|"Ancestor":||Dr. Arik Soong|
- "Dr. Soong's penchant for whimsical names seems to have no end."
B-4 was a prototype android constructed by Doctor Noonien Soong on Omicron Theta in the 2330s. Although B-4 was physically identical to both Data and Lore, the two final androids built, B-4 was not equipped with a positronic brain as sophisticated as those of his brothers, with the result that he asked simple questions such as "Why does the tall man have a furry face?", and describing Engineering as being simply "A room... with lights."
The existence of B-4 was not known to Starfleet until 2379, when the disassembled pieces of the android were found by the crew of the USS Enterprise-E on Kolarus III. The pieces had been planted there by Shinzon as part of an elaborate scheme to lure Jean-Luc Picard to Romulus. B-4 was also used as an unwitting spy; he was equipped with a second memory port that contained subversive programming that compelled him to download vital data about the positions of all Federation starships and their coded communications frequencies.
Although he recognized B-4's limitations, Data wished to give his brother the opportunity to expand his capabilities, much in the same way that he himself had in years past. Towards that end, Data willingly copied all of his memories to B-4, hoping that the added experiences would help B-4 to expand beyond his original programming. However, soon afterward, B-4 had to be deactivated because of the danger he posed to the Enterprise crew, as a result of Shinzon's tampering.
A short time later, Data was killed while destroying the Scimitar; having voluntarily sacrificed himself to save his crewmates. B-4 was reactivated, and although some of Data's memories began to surface, his future was uncertain. (Star Trek Nemesis)
- B-4 was played by actor Brent Spiner.
- In the original Star Trek Nemesis script, the android B-4 ("before") was named B-9 ("benign"). Also according to the script, the android was taken from its homeworld by the Pakleds and traded to the Bolians. He ultimately encountered some Cardassians, who tossed him into a garbage chute and out into space, where he was found by Talosians. It was also revealed that Shinzon had learned of the prototype android through a Cardassian historian. None of this, however, made it to the final version of the script.
- Captain Picard's interactions with B-4 after Data's destruction at the end of Star Trek Nemesis hint at the possibility of a Spock-like rebirth of Data through B-4, although actor Brent Spiner has called this unlikely due to the fact that he himself has "visibly aged out of the role" of an android who supposedly does not age. Of course, this is not necessarily true since the TNG episode "Inheritance" states that Data does, indeed, have the capability to age.