TF2 Health
Heavy		300
Soldier 	200
Pyro		175
Demoman		175
Medic		150
Scout 		125
Engineer	125
Spy			125
Sniper		125

	TF2 Damage
Normal 		50  - 120
Critical 	150 - 360
Melee		65

Minimal damage is variable (52-54). According to the wiki it's 50

Normal minimal takes 3 arrows to kill 5 characters (55%)
Normal minimal takes 4 arrows to kill 8 characters (88%)
Normal minimal takes 6 arrows to kill 9 characters (100%)

Normal maximal takes 2 arrows to kill 8 characters (88%)
Normal maximal takes 3 arrows to kill 9 characters (100%)

Critical minimal takes 1 arrows to kill 5 characters (55%)
Critical minimal takes 2 arrows to kill 9 characters (100%)

Critical maximal takes 1 arrow to kill 9 characters (100%)

Melee takes 2 hits to kill 4 characters (44%)
Melee takes 3 hits to kill 7 characters (77%)
Melee takes 5 hits to kill 9 characters (100%)



	Overwatch Health
Roadhog		600
D.Va		600
Reinhardt	500
Winston		500
Orisa		400
Zarya		400
Bastion		300
Doomfist	250
Reaper		250
Mei			250
Genji		200
McCree		200
Pharah		200
Soldier:76	200
Sombra		200
Hanzo		200
Junkrat		200
Torbjorn	200
Widowmaker	200
Ana			200
Lucio		200
Mercy		200
Symmetra	200
Zenyatta	200
Tracer		150

	Overwatch Damage
Normal 		29 - 125
Critical 	58 - 250
Melee		30

Minimal is variable (29-32). According to the wiki it's 29

Normal minimal takes 7 arrows to kill 15 characters (60%)
Normal minimal takes 9 arrows to kill 18 characters (72%)
Normal minimal takes 14 arrows to kill 21 characters (84%)
Normal minimal takes 18 arrows to kill 23 characters (88%)
Normal minimal takes 21 arrows to kill 25 characters (100%)

Normal maximal takes 2 arrows to kill 18 characters (72%)
Normal maximal takes 3 arrows to kill 19 characters (76%)
Normal maximal takes 4 arrows to kill 23 characters (92%)
Normal maximal takes 5 arrows to kill 25 characters (100%)

Critical minimal takes 4 arrows to kill 15 characters (60%)
Critical minimal takes 5 arrows to kill 18 characters (72%)
Critical minimal takes 6 arrows to kill 19 characters (76%)
Critical minimal takes 9 arrows to kill 23 characters (88%)
Critical minimal takes 11 arrows to kill 25 characters (100%)

Critical maximal takes 1 arrow to kill 18 characters (72%)
Critical maximal takes 2 arrows to kill 23 characters (92%)
Critical maximal takes 3 arrows to kill 25 characters (100%)

Melee takes 7 hits to kill 15 characters (60%)
Melee takes 10 hits to kill 19 characters (76%)
Melee takes 20 hits to kill 25 characters (100%)

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Summary:

In TF2 critical maximal kills everyone while in OW it kills 70%. You need 2/3 headshots at full power to kill the healthiest characters in OW.
In TF2 critical minimal kills half of the cast while in OW it takes 4 headshots to eliminate the same proportion of characters.

In TF2 normal maximal it takes 2 arrows to kill almost everyone (and a followup arrow will kill everyone) while in OW two bodyshots kills only 70% of the heroes. You'll need up to 5 hits depending on target.
In TF2 3 weakest shots will half of the cast (in OW it takes 7 shots) and 6 weakest shots will kill everyone (in OW it's up to 21)

In TF2 3 melee hits will kill majority of characters while in OW it's 7 hits.