Archtypes
The social engineer, who speaks the enemy langauge, can pose as an enemy officer, or act as distraction.
The Radio man. SO IMPORTANT, relay intelligence, call artillerists. Maybe not so good in a stealth mission, but calling reinforcements could help. Or "We need extraction! We're at (X,Y)! Etc. See Linguist below.
The scientific or political prisoner.
The combat engineer, builds bridges, bunkers, mans the radar, Etc.
The linguist. Read maps, interogate captured troops/civilians
And as for Assassinating Hitler, that only works if time travel is allowed. . .
Actually, that would be a fun mission too, despite the odds. . .