Anna Haining Bates, 7'11'' and her husband, Martin Van Buren Bates, 7'8'' (1870s)
From Wikipedia:
"Bates conceived two children with Martin. The first was a girl born on May 19, 1872; she weighed 18 pounds (8.16 kg) and died at birth. While touring in the summer of 1878, Anna was pregnant for the second time. The boy was born on January 18, 1879, and survived only 11 hours. He was the largest newborn ever recorded, at 23 pounds 9 ounces (10.7 kg) and nearly 30 inches tall (75 cm); each of his feet was six inches (152 mm) long. For this he was posthumously awarded a Guinness World Record."