Tracer is the call sign of Lena Oxton, a character who appears in Blizzard Entertainment's Overwatch franchise. The 2014 Overwatch Cinematic Trailer short was her first appearance overall. An April 2016 update for the crossover multiplayer online battle arena game Heroes of the Storm added her to its playable roster, marking her first inclusion in a video game. Shortly thereafter, she appeared in the first Overwatch game, a first-person hero shooter. She again appeared in its 2023 sequel, Overwatch 2.

In the Overwatch narrative, she is a peppy and energetic pilot of British origin. A damage-class hero in-game, Tracer has low health, but is highly mobile, being able to both teleport and time travel. Those abilities were caused by an accident that left her unable to maintain a physical form in the present until her friend and fellow Overwatch agent, Winston, invented the "chronal accelerator", a device that allows her to control her own time frame.

Prominently featured in the franchise's official media and serving as the first game's cover girl, Tracer is one of the most recognizable Overwatch characters and one of the more commonly featured in its fan art. Tracer has attracted media coverage related to online controversies surrounding one of her in-game victory poses, as well as her prominence in fan-produced pornography, which Blizzard has tried to remove. The character has appeared in Overwatch animated media and a digital comic series based on the game. In her comic debut, she is revealed to be a lesbian, a depiction that was positively received by media outlets and players.

Tracer was one of the first twelve Overwatch characters introduced at BlizzCon in 2014. Her in-game character model notably features tight orange pants, goggles and Crocs-like shoes. Her design is based upon an element from Blizzard's canceled project, Titan. Overwatch's game director Jeff Kaplan said Titan included a class of character called "Jumper", which developed into Tracer because Overwatch focuses on creating individual characters instead of generic classes. The Jumper class was depicted as male in most of the concept artwork and its player version. Like Tracer in Overwatch, the Jumper was equipped with the Blink and Recall abilities, as well as a Pulse bomb and dual-wielding machine pistols. The design of Tracer's pistols were influenced by the G18 pistols featured in Call of Duty: Modern Warfare 2.

Tracer's design was influenced by Geoff Goodman, the lead hero designer for Overwatch. Tracer was the first hero designed for the game and was used to test the basic gameplay. Kaplan recounted the first Overwatch playtest, stating, "The entire level was gray and blocky and the only hero was Tracer. We had no visual effects or attachment points on her guns so she just shot laser beams out of her eyes." Overwatch's assistant game director Aaron Keller has said Temple of Anubis was the first map developed for the game, and that the map and Tracer were worked on concurrently. Keller said, "One day we got both of them in, and just with Tracer running around an unfinished map it was fun". Keller said that, unlike other characters, Tracer's three abilities were maintained throughout the game's development, noting, "from the beginning, she originated as a 'whole' hero". However, her health pool was nerfed during the game's late closed beta stages. Concerning Tracer's gameplay style, Kotaku's Kirk Hamilton said "she's quick and squishy, designed more to harry the opposing team from behind than to survive a frontal assault".

Lead artist Arnold Tsang said the character's body size and running pose were considered during character design to make each hero easily identifiable. Tracer has a wild running animation and a unique trail of blue light extending behind her. Nathan Grayson of Kotaku said her jump animation appears "hyper-exaggerated and kinda goofy looking", a result of the smear frame and squash and stretch animation techniques used in Overwatch. Blizzard senior animator David Gibson pointed out frames from her jump animation: "We're trying to just push it a little further than normal. Something as simple as stretching the torso out, having her hang [in the air] just a little bit longer than normal. Really squashing her when she lands."

On the return of Overwatch's closed beta in February 2016, victory poses and other cosmetic changes were added to the characters. In March 2016, a controversy arose about Tracer's "Over the Shoulder" victory pose after a user on the game's forums said it was out of character and "reduces Tracer to just another bland female sex symbol". The post generated a discussion on the forums, which gaming outlets noted for its civility; several users added their own critical opinions of the pose while others disagreed with the original poster. Kaplan posted an apologetic response in which he announced Blizzard's plans to replace the pose because they did not want to "make someone feel uncomfortable, under-appreciated or misrepresented".

The decision was met with mixed reactions from the gaming community. Some argued that Blizzard had surrendered its creative control over the game, censoring content to appease an offended user, while others praised Blizzard's willingness to listen to the community and adhere to standards for portraying characters according to their personalities. Kaplan later said the game's development team was not "entirely happy with the original pose" and that internal creative struggles over its inclusion had occurred. The following week, a replacement pose was released; one commentator said this was "different, butt [sic] not by much", referring to the prominent buttocks of the original pose. According to Jessica Lachenal of The Mary Sue website, the replacement pose was inspired by a cheesecake pin-up illustration by Billy De Vorss. Kaplan called the replacement pose cool, cute, and playful, and said he wished the team had chosen it originally.