Apply penetrating oil and let it soak
Use the correct size socket or wrench
Tap the tool onto the bolt head for a tighter grip
Try locking pliers if part of the bolt is exposed
Use a bolt extractor socket
Cut a slot in the bolt head and use a flathead screwdriver
Heat the surrounding metal carefully
Strike an impact driver if the bolt is accessible
Drill a small pilot hole and use a left-hand drill bit
Use a screw extractor
Weld a nut onto the stripped bolt head
Drill out the bolt completely if removal fails
Re-tap the threads or replace the fastener after removal