Mike first appears in the episode "The Vanishing of Will Byers". Dustin, Lucas and Will are at Mike's home playing Dungeons and Dragons in the basement. Mike's mother declares that it is a school night, its after 8 o'clock and the boys need to leave. A Demogorgon has just appeared and Will casts fireball but misses. Will tells this to Mike, "The Demogorgon, it got me" then leaves. The garage lights flicker and Mike turns them off and goes inside.
"Wait a minute, did you hear that? That, that sound... boom boom BOOM! That didn't come from the Troglodytes, no that, that came from something else... THE DEMOGORGON!"
- Will Byers – Best Friend
- Lucas Sinclair – Best Friend
- Dustin Henderson – Best Friend