The Semquess were a race whose battle shroud was used by the Euterpians and the Greld, along with the Omnethoth, to destroy an entire galaxy in a battle to destroy a thousand of the Mad Mind of Bophemeral's fleets in the Millennium War. (PROSE: The Quantum Archangel)

Brokk stole valuable chemicals from the Semquess, who were considered the most skilled bio-engineers of their era. They shot down Brokk's ship as he tried to escape, which forced him to land on Earth in 1884. They tracked him down fifty years later, destroying his ship with the indirect aid of the temporally-displaced Third Doctor and UNIT from 1970. (PROSE: The Eye of the Giant)

The Semquess language featured underwater communication and the use of their multiple limbs. (PROSE: The Eye of the Giant)