Vlenn was a male Deltan sociologist assigned to covert research on the planet Mestiko in the mid-2260s. Vlenn was the most experienced of the three person Federation team on Mestiko when a rogue pulsar was detected moving toward the Mestiko system.

Vlenn remained on Mestiko following this discovery, and died in 2265 a result of the pulsar's passage through the system. (TOS eBook: Mere Anarchy: Things Fall Apart)