Igor Sergei Valenko (Bentley Calder) was a KGB agent with ties to Irina Derevko. Like Irina, he faked his death.
Before Season 1
Igor was working for the KGB along with Irina Derevko, earning the nickname "Spy Hunter". Somewhere along the line, he feigned his death along with Irina.
K-Directorate placed a hit out on Khasinau and sent a hitman nicknamed Snowman to kill him. Since the Snowman couldn't locate Khasinau, he decided to look for one of his contacts, which happened to be Calder. Sydney and SD-6 also realized that Calder was in danger and needed to find him fast, so they sent Sydney to Australia. Unfortunately, Sydney was only a few minutes too late; she found all of Calder's guards dead and as soon as she entered the kitchen, she saw the hitman stabbing Calder.