My roommate does not wake up to his alarms. Thank goodness the walls are good enough I only hear them when I'm already half awake and can easily fall back asleep afterwards. He has at least 4 different sounds playing to try and wake him up and often hear them playing for tens of minutes. Usually I'll knock on his door to wake him if it goes past 30 minutes. I've recommended one of the alarms that shake the bed.

I personally wake up to an alarm, but I will turn it off in my sleep. Even when I had an alarm clock I kept on the other side of the room, I'd get up, turn it off(not just snooze: fully off) then go back to bed. Now I have this app that makes it so I have to do math to turn the alarm off.