Like all the members of the crew of the original Enterprise, Chekov has become something of a legend in Starfleet history. Relatively little is known about his early life; he was born on Earth in Russia in 22451, an area that he would be fiercely proud of throughout his life. Indeed, Chekov had a habit of proclaiming that just about every major historical event or person was Russian.2
During his Academy years Chekov met and fell in love with Irina Galliulin, a fellow cadet. The two enjoyed a romantic involvement, but Irina found both Chekov and Starfleet to be too inflexible and formal for her own taste, and she eventually dumped him and dropped out of the academy. Chekov would meet her later when she was rescued from the space cruiser Aurora as part of a group led by the alternative lifestyle guru Doctor Sevrin. Chekov still had feelings for Irina, but she betrayed him in order to assist Sevrin. Despite this, the two parted on friendly terms.3
After ten years on the Enterprise, Chekov was promoted to Commander and assigned as First Officer of the USS Reliant. Whilst the ship was searching for a lifeless planet for use in phase three of the Genesis project, Chekov was captured by Khan Sing on Ceti Alpha Five. Khan used a native parasite in order to gain control of Chekov's mind and used him to hijack the Reliant and attempt to steal the Genesis device, but Chekov's body rejected the parasite and he was able to participate in the final battle against Khan. Acting as weapons officer on the Enterprise, it was Chekov who fired the shots which crippled the Reliant.4
He took part in Admiral Kirk's theft of the Enterprise in order to recover Captain Spock's body from the Genesis planet.5 Later he served aboard the Enterprise-A;6 like many of Kirk's crew he refused promotion or transfer in order to stay with his comrades despite having a rank and seniority far higher than his position merited. Chekov remained on the Enterprise for the rest of his career before he finally retired in 22937 aged forty eight.
Shortly after his retirement Chekov was attending the launch of the Enterprise-B when the ship attempted to rescue a group of El-Aurian refugees caught up in the Nexus - the mission in which James Kirk was believed to have been killed. He acted as the ships nurse for the mission, where he briefly met Guinan and Doctor Tolian Soran.8