The Tyrant race is one of the few races that are still referred to as Clans in the later officially translated games though they seem to have reverted to a Race in Devil Survivor 2. Generally, Tyrants are the major enemy of their respective chief deity or otherwise demonic lords. They are always Dark-Chaos and belong to the Magica species.
Tyrants are the most powerful Dark race, and also one of the most powerful races in general. They're great at everything they do and have no major weakness. Tyrants are basically the Dark version of the Deity race and are just as difficult to fuse. Another race related to the Tyrant are the Fallen, which can be considered a Neutral LND Counterpart.
Tyrant demons are bosses, each faced once. In Kyuuyaku Megami Tensei they all have identical resistances: taking half damage from physical attacks and electric spells, slightly less than half from expel magic, taking only 25% damage from ice and force spells, and reflecting fire spells back at the user for half damage.
Tyrants cannot be recruited through negotiation (even with Jive Talk) and must be fused. Tyrants only rank-down when being fused with any Element, unless the Demi-fiend has been cursed by his own Magatama, in which case any Element will trigger a rank-up fusion instead.
"The numerous demon lords who represent and direct Fallen demons. Lower-Leveled Tyrants are concerned only with advancing their own power, while the higher-classed Tyrants seek to realize a universe with a completely different order from that of the Creator."
Thanatos was the sole member of the Reaper Order in the PS version, but had his order changed to Tyrant in the PSP port. The other members were Tyrants in the PS version but had their orders changed to Deity in the PSP port (except for Lady Snow, who became part of the Karma Order).
The Tyrant race has the Tyranny Racial Skill, which restores MP to the team according to the damage inflicted, along with delaying the turn of the opposing team after combat. The Tyrant race is also notable in that every member of this race is Unique.
The Tyrant race has the Tyranny Racial Skill, which restores MP to the team according to the damage inflicted, along with reducing the combat initiative of the opposing team, reducing their chances of getting initial Extra Turns. Stronger Tyrants have this skill changed to Blood Treaty, which grants an additional option which will triple the power of any recovery or draining ability for the team, including their innate MP recovery. This also means that skills like Drain and Life Drain inflict 3 times as much damage. The Tyrant race is also notable in that every member of this race is Unique.
* Asterisk denotes race that has been put under different species throughout the series. Italic font denotes the race/species name (not in katakana for Western loanword) has not yet received any official English localization.