Table: Helmets (Chrono Trigger) General

Helmet
Type
Defense
Obtain
Effect
Sell
Aeon Helm
All
33
Ocean Palace - Chest/Last Village - 7800G, only after meeting Magus/Sunken Desert - Chest
3900g
Angel's Tiara
Females
36
Dimensional Vortex - Chest
Auto-haste, status immunity
Beret
All
17
Sold in A.D.600 Porre for 700G
350g
BronzeHelm
All
8
Millennial Fair - 200g/Porre Market, 1000 A.D. - 200g/Truce Market, 600 A.D. - 200g/Truce Market, 1000 A.D. - 200g
100g
CeraTopper
All
23
Tyrano Lair: Chests (2)
1250g
Dark Helm
Males
35
Death Peak - Chest
Cuts Shadow damage by 50%
6000g
Doom Helm
Magus
29
Magus's initial helmet
4750g
Dragonhead
Males
36
Lost Sanctum - 20000g, Chest
Strength +5
10000g
Gloom Helm
Magus
42
Ozzie's Fort - Chest in hidden room
Protects Status
6500g
Glow Helm
Males
25
Medina - 1717g/Algetty - 2300g
1150g
Gold Helm
Males
18
Get from Knight Captain on the 600 A.D. Zenan Bridge after feeding the army and choosing to help fight/Chest: Denadoro Mts
600g
Haste Helm
All
35
Black Omen - Chest/Black Omen - Charm from Lavos Spawn (head)
Always Haste status
6000g
Hide Cap
All
3
Crono's initial helmet
25
Iron Helm
All
14
Arris Dome - 500g/Trann Dome - 500g
250g
Lode Helm
All
29
Mt. Woe: Chest
3250g
Master's Crown
Males
40
Dimensional Vortex - Chest
Damage boost, status immunity
Memory Cap
All
30
Death Peak - Chest/Sunken Desert - Chest/Fiona's Shrine - 20,000G
Prevents Lock
10000g
MermaidCap
All
35
Terra Cave - Charm from Blue Beast
Cuts Water damage by 50%
8000g
OzziePants
All
45
Ozzie's Fort - Charm from Great Ozzie (two chances)
Causes Chaos, drains HP
Prism Helm
All
40
Complete the Sun Stone Sidequest/Zeal (right hand) - Charm
Protects Status, Magic Defense +9
4400g
R'bow Helm
All
35
Terra Cave - Charm from Beasts
Cuts Lightning damage by 50%
8000g
Reptite Tiara
Female
35
Lost Sanctum - 18000g, Chest
Magic +5
9000g
Rock Helm
All
20
Ayla's initial equipment/Ioka Trading Hut: Trade 3 Horns and 3 Feathers (before Ocean Palace Incident/Reptite Lair: Chest
1000g
Safe Helm
All
38
Forest Ruins - Unseal with pendant and choose left chest/Black Omen - Charm from Lavos Spawn (shell)
Cuts physical damage by 1/3
5000g
Sight Cap
All
30
Ozzie's Fort - Chest/Giant's Claw - Chest/Fiona's Shrine - 20,000G
Prevents Chaos
10000g
Taban Helm
Lucca
24
Get from Taban after first visit to 65000000 B.C.
Magic Defense +10
Time Hat
All
30
Mount Woe - Chest/Fiona's Shrine - 30,000G
Prevents Stop and Slow
15000g
Vigil Hat
All
36
Geno Dome - Chest/Fiona's Shrine - 50,000G/Black Omen - Chest/Black Omen - Charm from Mega Mutant (bottom)
Protects Status
25000g

From: Armor (Chrono Trigger)