Boris Zorotov was a communist intelligence agent who appeared in Biggles in the Blue and No Rest for Biggles. What his nationality was and which specific intelligence agency he worked for was never mentioned. In both books, he appeared to play the role of a "minder" to Erich von Stalhein, exploiting von Stalhein's talents while making sure he did not step out of line. It was not even clear that Boris Zorotov was his real name--this was merely the name he used to check into a hotel in Kingston, Jamaica. Von Stalhein had used the name Ernst Stalling at that time.
Biggles first encountered Zorotov in Kingston, Jamaica. There, Zorotov as acting as a "stooge" or decoy for von Stalhein (although it would later be clear that he was actually senior to von Stalhein and gave the orders). Taking advantage of their slight resemblance, Zorotovv had wrapped himself in a bathrobe, put on a monocle and smoked with a long cigarette holder by the hotel swimming pool, thus fooling observers that it was actually von Stalhein who was lounging there. This left von Stalhein free to conduct his operations--specifically hunting for Werner Wolff's secret documents at Rumkeg Haven. When Biggles finally discovered the deception, he noted that the resemblance to von Stalhein was only superficial. Zorotov was slightly heavier built and flatter in the face. Ginger also noted a stricking cold-blooded absence of expression in his eyes.
Biggles and co. encountered Zorotov again on Inagua where he was leading his party comprising von Stalhein and Napoleon Morgan in search of Werner Wolff's cache of documents. When face to face with Zorotov and von Stalhein, Biggles took the opportunity to draw a unflattering comparison between the two--Biggles wondering why an officer and a gentleman like von Stalhein would work for someone "brought up in a sewer" like Zorotov. The arguments which broke out between the two on how to handle matters showed that Biggles' words had struck home.
Biggles next met Zorotov in Liberia in No Rest for Biggles. Here Zorotov and von Stalhein had travelled to Christophe's jungle camp to try to secure the American secret weapon which Christophe had stolen. Biggles was at that time Christophe's prisoner together with several others, the members of an R.A.F. V.I.P. flight which Christophe had brought down using his secret weapon. This time, von Stalhein tried to doublecross Zorotov by bribing Biggles. Von Stalhein offered to free Biggles with a pair of wire cutters if he would fly him and the secret weapon away. Zorotov spotted von Stalhein at the wire speaking to Biggles and not trusting him, approached to find out what was going on. Von Stalhein promptly shot him to keep him quiet.