First Strike is a medal awarded in Halo: Reach, Halo 4, Halo 5: Guardians, and in all multiplayer modes in Halo: The Master Chief Collection (save Halo 3) for scoring the first kill in a Multiplayer round or match. Although awarded only once in a standard one-round game, it is awarded multiple times in gametypes with multiple rounds such as Grifball, Infection, Flood, 1 Flag CTF and Sing Bomb Assault.
- The Medal is a reference to the Halo novel titled "First Strike" and the common term "First Blood" in many other games.
- A bug in the multiplayer beta caused this medal to be reset upon leaving a host migration; the first player to score a kill thereafter earned the medal.
- The achievement "Yes, Sensei" is unlocked upon earning a First Strike Medal in matchmaking. Once the achievement is gained you also unlock the UA/Base Security [W] armor from Halo Waypoint.
- In the postgame stats, this medal will always appear as the top medal of any game.