SM UB-86 was a German Type UB III submarine or U-boat in the German Imperial Navy () during World War I. She was commissioned into the German Imperial Navy on 31 October 1917 as SM UB-86. UB-86 was surrendered to the British on 24 November 1918 in accordance with the requirements of the Armistice with Germany. On her way to Falmouth, Cornwall, UB-86 and three other u-boats stranded and were broken up in Falmouth in 1921.