AGPO:
Who are the toughest of the tough in your country’s armed forces?
For the UK, the SAS are world famous in terms of special forces, but in terms of ‘regular’ troops, the Royal Marines 3 Commando Brigade are the toughest of the tough, alongside the Royal Gurka Rifles. Apparently there’s a band of PE instructors in maroon berets who are pretty hard too. Parras or something…
Willmark:
The US hgas quite a few:
The Green Berets
Army Rangers
SEALS
Marine Force Recon
Rangers
Delta Force
And those are just the ones we know of.
snowblizz:
Delta ForceIsn't that Chuck Norris movie? :~
Willmark
Fallen246:
Fix'dDelta ForceIsn't that CHUCK NORRIS?
Willmark
snowblizz
AGPO:
It’d be interesting to know how US elite and special forces training differs from that in the UK. A mate of mine has just completed P-Company and earned his maroon beret. Still a way to go before he’s a paratrooper though. The Commando course is supposedly (according to the RMC anyway) the toughest traingin you get outside selection
Swissdictator:
The toughest soldiers ever? The Iron Brigade. 
Ishkur Cinderhat:
Austria has a quite capable counter-terrorism unit. Funny enough the unit name derives from the German title of the 70’s TV show “Mission Impossible” which must have been quite popular back in the days when the unit was created 
Grimstonefire:
The russian spetsnaz are tough guys as well. I would have said for regular (non special) forces the commandos are the best in the UK. Their training is very long as well I believe, much like all our armed forces.
Swissdictator:
What about historical units? I mentioned the Iron Brigade from the American Civil War. While nothing compared to the modern units due to tactics and weapons, they were quite tough in their time.
In that case, the units name fails me, but the Americans armed with rifles during our Revolution were pretty good.
Servius:
In the world…
Hrm… Tough… Very Tough.
Single Soldier - Probably A SEAL - UDT Specialist.
Single Unit - Soviet Army Spetsnaz (the unit size was enormous (26 to 32 men) and the Soviet Training was by far the longest and toughest… Started at 11 usually.
Best Trained in general… I would put this up to the British S.A.S. and US Delta Force. their training is usually standard soldier, then specialization, then Special Ops, Then additional training in weapons of other countries and tactics.
Pretty much Unstoppable… WWII Era British Gurkhas - they were batsh*t crazy and would take Ruger rounds to the chest and keep charging.
Bravest Soldiers of all time… WWI Era Australian 10th Light Cavalry at Gallipoli! Sweet Jesus… considering that they went nearly 7 minutes AFTER shelling ended + after seeing a previous charge from an active and veteran Infantry Division basically crumble to Turk machine gun fire… They knew they were dead. and they still took to the no-mans lands all the harder.
Captain Crayon:
Australian SAS 
The evil army general is marching his forces through the desert when he hears
“hey! there’s and Australian soldier over here! come get him!”
The general promptly sends 10 of his men over the dune and he is rewarded with masses of gunfire and screaming then silence…
“Come on! there’s only 1 Australian over here!” comes the call from over the dune.
He sends over a full Platoon… fighting, gunfire, screaming then silence…
Not one of his soldiers had returned… He sent over 3 full platoons. They charged over the dune, banners waving and the sounds of battle raged for well over an hour, then silence. A lone ragged, bloodied soldier stumbled and fell over the lip of the dune, tumbling down and falling at the general’s feet.
With his last breath he croaked…
“They lied… there were 2 of them”
…
Don’t forget the Australian light horse either!
Charging the turkish guns to take Beersheba in 1917… Allegedly the only successful mounted infantry charge in history.
Fallen246:
Us Aussies also have a wicked Intelligence agency.
Although, all it does is gather intelligence, they don’t have secret agents…
…That me, you, or anyone else knows of…
GRNDL:
re: Single Unit - Soviet Army Spetsnaz (the unit size was enormous (26 to 32 men) and the Soviet Training was by far the longest and toughest… Started at 11 usually.
Spetznaz aren’t a single unit. The name refers to any troop unit with a special purpose, so in general, they’re not like SAS, SEALs, etc.
26-32? Try 30,000… Even the specialist “alfa” counter terrorist group has 700 in it.
http://en.wikipedia.org/wiki/Spetsnaz