I'm going to repeat some in the interest of having a complete list. Paraphrasing the definition introduced in Second Sight, a lesser/minor template has 3 facets: 1) still mortal 2) has powers 3) able to be overwritten by major template.
I'm also including a link to my similar RPG SO answer:
Rules for gradual transformation from mortal to template in nWoD? If anyone is aware of additional minor templates, please let me know in a comment and I'll add them.
World/Chronicles of Darkness mortals
Mortals with Skill Tricks, which are astounding applications of normal skills that might surprise even supernatural types and each comes with a Plot Hook.
Covered in: World of Darkness: Mirrors p. 52-69
Forbidden Lore, Conviction & Expanded Willpower
Optional systems for allowing mortal characters to pack more punch against the strange, sort of building your own minor template. Forbidden Lore offers supernatural boons in exchange for sanity, the human spirit powers Conviction, and Expanded Willpower is mostly what it sounds like: more ways to use Willpower.
Covered in: World of Darkness: Mirrors p. 28-33
There are multiple types (from blood-bathers to body-thieves to people who've basically become spirits) and depending on how you want to treat them, they might be major-template-able.
Covered in: Immortals
A mortal who shares their mind and body with a demon.
Covered in: Inferno Chapter 3
Psychic is kind of a catch-all, if we're honest. Almost every power could be construed as psychic and anything listed as a psychic power could be Storytold as having some other origin.
Covered in: Second Sight, Chronicles of Darkness as Supernatural Merits, Hurt Locker(?)
Mortals who steal the shapes of animals by wearing their skins.
Covered in: Skinchangers, but summarized and updated for 2nd edition on Dark Eras p. 248-249.
Technically intended as a strictly antagonist template, they are still mortal and could theoretically be Embraced, undergo First Change, Awaken, etc. Keep in mind that this template and its Merts are meant to keep a whole troupe busy, so they are often purposefully unbalanced compared to individual characters.
Covered in: World of Darkness: Slasher (the most Hunter of non-Hunter books)
Mortals who have learned how to use Low Magic.
Covered in: introduced in Second Sight
Vampire: the Requiem
Mortals who drink vampire blood for immortality, healing and sometimes learn vampire Disciplines. CAUTION: after the 3rd feeding from the same vampire, the ghoul develops a Vinculum, a supernatural emotional dependence on that vampire.
Covered in: Existed in VtR1 and had their own sourcebook, Ghouls. Vampire: the Requiem 2nd Edition and Half-Damned would have the most recent rules.
Dhampir / Dampyr
Mortals descended from vampires.
Covered in: First mentioned in Night Horrors: The Wicked Dead (there as dampyr), but recently fleshed out further in Half-Damned.
Werewolf: the Forsaken
Mortal relatives of werewolves. Blood of the Wolf provided expanded rules for wolf-bloodedness.
Covered in: Werewolf: the Forsaken, Blood of the Wolf
Most mortals can't really access the powers of spirits that are urging them, but some might so I'm counting them here.
Covered in: For probably the best example of mortals using spirits like this, see the Rites Du Cheval from HtV:Spirit Slayers.
Mage: the Awakening
Sleepwalkers can view and remember Supernal magic and do not contribute to Disbelief.
Covered in: Mage: the Awakening 2nd edition
Proximus (plural: Proximi)
Mortals who's lineage or life has been touched by the Supernal. They receive some mini-Mage powers and have a Curse that acts as a persistent Condition. Instead of getting Paradox from spells, their Curse gets worse.
Covered in: Mage: the Awakening 2nd edition p. 307-309, a 2nd example lineage exists on Dark Eras p. 110-111. First mentioned in MtA1, fleshed out in The Silver Ladder.
Mortals that have been educated and initiated by the Silver Ladder and now run the order's Cryptopoly cells. While not necessarily magical themselves, they would certainly have the connections and clout to request magic. Some Illuminated are also Proximi.
Covered in: The Silver Ladder
Hunter: the Vigil
Hunters themselves check all the boxes for being a minor template. In addition to the main set of Endowments, the book Compacts & Conspiracies introduces special Merits for the Compacts. Keep in mind also that there are additional Conspiracies and Compacts in pretty much every Hunter supplement, so check those out if you don't like the core-book's ones.
Covered in: Hunter: the Vigil, Compacts & Conspiracies.
A Merit for Mortals who have access to specific Gutter Magic-like abilities.
Covered in: Witch Finders p. 139
Geist: the Sin-Eaters
Some mortals can open Avernian Gates. They don't get any other powers explicitly, but could be combined with Supernatural Merits or Second Sight stuff to flesh them out.
Covered in: Book of the Dead p. 50-51
Demon: the Descent
Humans exposed to the God-Machine and marked by it.
Covered in: Demon: the Descent
Children of demons, adopted or biological.
Covered in: Heirs to Hell
Changeling: the Lost
Mortals who are able to see fae magic for what it is, typically granted by a changeling through a Pledge.
Covered in: Changeling: the Lost
First introduced as mortals who have been to Faerie but had not undergone the complete transformation into changelings. As another answer noted, 2nd edition draft rules allow them to also be mortals who had powerful promises to the changeling and wandered into the Hedge looking for them.
Covered in: Equinox Road, Changeling: the Lost 2nd edition (not out yet)
Promethean: the Created
Prometheans who have completed their Great Work and become mortal. They might retain some memories or supernatural powers, particularly if they maintained an Athanor.
Covered in: Promethean: the Created
Child of a Promethean. Seemingly immune to Disquiet.
Covered in: Magnum Opus
Mummy: the Cursed
Mortals immune to Sybaris, an aura of awe & despair that mummys give off. They're somewhat like Mage's Sleepwalkers, except Witnesses are mechanically drawn to mummies (Sleepwalkers have no especial compulsion).
Covered in: Mummy: the Cursed p. 83-84
Half-alive, mystically-bound servants of mummies. They sleep when mummies "die" and awaken when their masters return. I'm not sure if they're greater-template-able, though.
Covered in: Mummy: the Cursed p. 188-192