Races
Base ClassesBarbarianBard: With so many mind effects, the bard is a master of mind effects. It forms the basis for the Sublime Chord, has excellent skill points, and has many of the class skills required for other fear classes. Using Inspire Awe makes the bard very useful, and the excellent Doomspeak is probably the best debuff in the game.
Cleric: Not as strong with fear effects, the cleric is always a powerful class. Doom, as a first level spell, makes cleric an excellent dip, if nothing else.
Fighter: With access to so many tactically useful feats, and with intimidate, the fighter is a terrifying opponent. Often used as padding to grant more feats easily, the zhentarim fighter is, by itself, a devastating class. I would love to see a combination Dungeoncrash-Trip-Fear Fighter. Real battlefield control, right there.
Paladin: Particularly for the half-orc, the paladin is a high-charisma class, which can be very powerful. Paladin synergises well with sorcerors, clerics and bards, and the half-orc paladin ACF is very nice.
Sorceror: Another high-charisma class, the sorceror can churn out a lot of fear effects. Their natural high charisma makes it very hard to resist many fear effects.
WizardDread NecromancerBindersFor those using the Tome of Magic, Chupoclops & Focalar are fantastic at debuffing, which is vitally important in fear effects.
Vanus has a great fear aura, too.
Prestige Classes
Acolyte of the Skin: The 3rd level ability, albeit once per day, is awesome: You automatically make an enemy shaken for ten minutes, and you stun them with a failed Save. The duration and automatic effect makes this an excellent dip, albeit losing some caster levels. Characterful and dramatic.
Avenging Executioner: Nongood, but otherwise it is a very characterful, dramatic class, that just happens to be devastating for the sneak attacker / demoraliser. Rapid Intimidation makes demoralising a move equivalent action, and bloody murder forces a fear effect if you drop an enemy. Add in some sudden strike damage, and this is a very effective class.
Champion of Gwynharwyf: When a 4th level Champion of Gwynharwyf enters a rage, you make an Intimidate check. Any enemy that comes within 30 feet of you while you are raging must make a Will save against a DC equal to your Intimidate check result. Those who fail become shaken for 1d4+1 rounds or the duration of the rage, whichever is longer. In short, if someone comes near you (say, someone fleeing from another source of fear), they get hammered again.
Dread Witch: Simply put, the Dread Witch is the best class for a fear caster. One dead level, and after that, it is magnificent. You can burn through fear immunity, boost your save DCs, reflect fear back on the originator, and delay fear effects so that they all hit at once. Just an excellent class.
Evangelist: The 3rd level Inspire Dread ability can lower saves dramatically, making this class potentially useful.
Mindbender: As many have stated, one level is enough. There is nice synergy for prerequisites with (for example) Nightmare Spinner.
Mystic Theurge: A useful filler class for a dual caster. The use of the Versatile Spellcaster / Heighten Spell combination for early entry can be a useful synergy.
Nightmare SpinnerScarlet Corsair /
Dread Pirate
Shadowcraft Mage: The class has been discussed
here and
here. It is a very strong, very powerful class; with very little tweaking, mostly via Nightmare Spinner, it is lethally scary.