Richard Jack (died 1759) was a Scottish mathematician, astronomer, and engineer active in the mid-18th century. He provided the only testimony against Lt. Gen. John Cope at the court martial following the Battle of Prestonpans during the 1745 Jacobite uprising, but Having exaggerated his own accomplishments and lacking corroboration, Jack had his testimony discounted by the judges, who found Cope blameless. Jack was later involved in the development of achromatic lenses and his work on conic sections was a source for the mathematical sections of the first edition of the Encyclopaedia Britannica.