Vivian Stranders (1881–1959) was a British-born Royal Air Force officer, German spy, and Nazi propagandist.

[4] He transferred to the Territorial Force's 1st (City of London) Brigade of the Royal Field Artillery as a second lieutenant on 8 August 1914.

[4][9][3] Stranders transferred to the Territorial Force Reserve on 2 July 1916, by which time he held the temporary rank of lieutenant.

[11][12][13] He was appointed to the more senior position of equipment officer 2nd class on 1 July 1917 and granted temporary rank as lieutenant in that role.

[2] After relinquishing his staff role on 8 September 1919 Stranders became a flying officer (equivalent to lieutenant), the RAF having adopted its own unique rank structure since his appointment.

[2][12][17] He provided his services as a translator and also helped to observe German compliance with disarmament agreements, including the transfer of Zeppelin aircraft to the Allies.

[20] Stranders left Germany on 21 January 1921 when he was demobilised from the RAF, being transferred to the unemployed list; he received permission to use the rank of captain in retirement.

[22][3] Because of restrictions imposed by the Allies on German military manufacturing these types of imports provided the majority of engines for German-made aircraft of the period.

[2] He was detected by the Secret Intelligence Service (SIS) while trying to secure British and French military information from a Belgian person.

[17] On 31 July 1926 the head of the Security Service, Sir Vernon Kell, passed papers to the Metropolitan Police that alleged Stranders was a bigamist.

[24][22][9] In connection with the case British Special Branch officers raided a property in Brixton, London, in early January 1927 and spoke with an Englishman and an Austrian man.

On 11 February the Member of Parliament for Shrewsbury, Viscount Sandon asked the Under-Secretary of State for Air, Sir Philip Sassoon, if Stranders still held a position in the RAF Reserve and received the reply that he did not, despite contrary press reports.

[28][9][22] Stranders was released from French prison after 18 months and returned to Berlin where he worked as a journalist, writing to oppose the restrictions imposed on Germany by the Treaty of Versailles.

[22] At the outbreak of the Second World War in 1939 he sought a high-level Nazi Party appointment in Berlin but instead was employed as an English-speaking propaganda broadcaster, under the name "Mediator".

[3] That summer he was appointed to the Nazi Schutzstaffel (SS) headquarters as an expert on the United Kingdom with the rank of SS-Sturmbannführer (equivalent to major).

[22] British prosecutors could not charge him with treason as he held German citizenship at the time of his propaganda work and he was released.