This is not a complete or comprehensive list, just incidents that have come to my attention.
Please feel free to forward any similar stories you find.
Defender fires AR-15 at suspects in Haiku, Hawaii home invasion robbery Star Advertiser
Good Guy with AR-15 Stops Attacker – Witness to stabbing grabs AR-15 and stops knife wielding attacker from inflicting further harm. Attacker runs, later captured by police.
Former NRA Instructor Engages Texas Church Shooter, helps chase him down until Law Enforcement arrive – Live video interview with the hero, the same day as the shooting here
Two gun store employees fight off five armed robbers, capturing two. Houston Chronicle
Store owner uses AR-15 to defend himself after 3 robbers use vehicle to smash in front door. Fox 6 Milwaukee
Homeowner shoots intruder in Vance County Break-in – Man in bed when armed intruder kicked in backdoor, homeowner grabbed AR-15 from under his bed, intruder shot once and missed. Homeowner shot back once and hit the intruder in the stomach.
Armed robbers driven off from holding up tax preparation business by security guard with AR-15. Fox 2 Detroit
No Shots Fired: Home Intruders decide not to stick around after seeing their victim holding an AR-15 – Two intruders break into apartment, encounter one student with an unloaded AR-15, choose to retreat. Original story from the Internet Archive Additional article from Washington Times
15-year-old Defends Home Against Burglars, Shoots One with Father’s AR-15 – 15-year-old boy home with only 12-year-old sister when burglars tried to break in. Burglars fled, leaving trail of blood. Original story from the Internet Archive
Pizza Hut delivery guy held up by three teens, grabbed AR-15 from car and teens ran off. He had been to the range before work. Pizza Hut fired him. NRA News
1992-04-29 – 1992-05-04
LA Riots – Many Korean store-owners and employees defended their businesses using handguns, shotguns, and semi-automatic rifles. Pictures can be found of defenders using Mini-14s, M1 Carbines, and Daewoo K1A1s