During a jump, have you ever had to deploy your reserve parachute?

I didn't have time. I reached up to pull my slip for landing...wound up holding my canopy silk. Bad juju, but a few seconds later I was on the ground, confused about why I couldn't stand up.
Lol, medic told me to stop moving, called a MEDEVAC, the chaplain came over and started praying. It turned out to be a great story, and after reconstructive surgery, I've still had several deployments and still run more than 90 points on my 2 mile run.

I did have a friend in Italy who had a Total Malfunction. Pulled his reserve, landed just fine with no injuries.

Nope, never had to deploy my reserve, in a lot of jumps up to and then well past JM school and earning my senior wings, had only two jumps where I had interactions with other jumpers and never with the aircraft.
Now landings, ya, had a bunch of bad landings.

CPT Aaron Kletzing, I NEVER had to dump my reserve, EVER, on a military jump. However, as a civilian skydiver, I did have a malfunction that required a breakaway from my main, return to free fall, and then I pulled my chest reserve. Unlike Army practice which is to retain the main canopy and deploy the reserve (at least when I jumped), generally civilian skydiving practice is to breakaway (cutaway) from the main, return to free fall and pull the reserve.
I had performed a routine 30 second delay from 7500', separated from the other jumpers, and then pulled. I checked my canopy and had a Mae West (see photo). They can be dangerous, because with a descending round canopy, much of the area designed to catch air is gone. Your rate of descent increases dramatically. It was totally my fault, as civilian jumpers pack their own main parachutes.
I cutaway from the main and went back into free fall. Since the canopy releases are on your front shoulders, you begin to fall backwards (inverted) and the reserve was on my chest. I pulled, and the pilot chute just lay there, as the spring was old (and not springy)! I screamed SXXT, pushed the pilot chute off my stomach and it caught air and the reserve deployed. I had an uneventful ride down, and landed on the DZ.
We retrieved the main canopy and it was not significantly damaged.
By then, I was already a USPA licensed advanced parachutist and a rated jump master and instructor, so I immediately chuted up again, took up three students, put them out and jumped again!
Was I scared? Yep. But the training takes over and you take care of business. I was also lucky, because some have not been so fortunate (thinking of the Navy SEAL this past weekend).
I was also licensed by the FAA to pack reserves and saw a jumper ride down a reserve I packed. That was immediately scary but ultimately most gratifying as the jumper enjoyed a nice ride down on the reserve that I packed! LTC Stephen F. 1SG(P) (Join to see) SSG Chris Erickson LTJG (Join to see) CPT (Join to see) MAJ Javier Rivera

I have never had the need to use mine. It happens, it is rare but it happens. It is much more likely to use it when you don't need to then to ever have the need to use your reserve chute.

Never had a malfunction on a military jump but did doing civilian skydiving. My fault. Training kicked in and I landed just fine with reserve. We recovered my main and then I bought the jump master who packed my reserve a drink.

CPT I was on jump status for more or less 20 years, I have no idea how many jumps I have, its a bunch out of all kind of A/C. I am not sure how many pair of foreign wings I have but I have never had to pull my reserve. Never! Thank God! I was even a jump master but the truth is jumping was not my favorite thing to do. I did it so I could do all the other cool stuff we did, not to mention it was part of the package. It was not always without incident, I have seen a few bad things on the DZ and those are the things you take up with you every time you put a chute on. Even on a bad day I would never have changed what I did. Oh, when I was young I heard there were two kind of jumpers; 1) tree jumpers 2) those who were going to be tree jumpers hahahaha

CPT from one paratrooper to another I wish you the best, don't run with the wind and keep your feet and knees together.

I've got a little over 50 jumps and I've never had to pull mine.

I had a cutaway on a MFF Jump, does that counts?

I have seen static line reserves deployed about a half dozen times and I had to deploy my reserve on a HALO jump at Luzon DZ at Camp Mackall.

Whille not a military jump, I went behind a fellow that did. On the ground, he told me all the way down he was saying to himself, ton of shit, ton of shit.