Tan Ru

From Memory Alpha, the free Star Trek reference.

Tan Ru was an advanced alien probe of unknown origin, programmed to collect and sterilize soil samples, possibly in anticipation of colonization.

In deep space, Tan Ru eventually encountered the Earth probe Nomad, which had suffered a serious loss of memory after a collision with a meteoroid. When the two probes met, directives from Tan Ru were transferred and merged with those left in Nomad's memory banks. This created a probe with the unintended directive to "seek out and sterilize new life," with Nomad as the body and predominant voice during their co-existence. (TOS: "The Changeling")

Jack Treviño, a writer who pitched several stories to Star Trek: Deep Space Nine, once pitched a story to Star Trek: Enterprise about the crew of the NX-01 encountering Tan Ru. This never came to fruition.