Three conjugation groups, with different kinds of regularity
French sorts every verb into one of three conjugations, and the split is not evenly weighted. Wikipedia's (checked 13 October 2026) "French conjugation" entry puts the first group, verbs ending in -er, at around 6,000 members, following the same pattern "largely without exception." The second group, -ir verbs whose present participle ends in -issant (finir → finissant), holds around 300 members and is also close to fully regular. The third group is everything left over: verbs in -re, verbs in -oir, a smaller set of -ir verbs that do not take the -issant pattern, and, despite its spelling, aller. Wikipedia states the exception directly (checked 13 October 2026): "aller, though it ends in -er, belongs to the third group."
The third group differs from the other two in shape, size, and status: per Wikipedia (checked 13 October 2026), the third group is a closed class, meaning no verb newly coined in French is ever assigned to it. OQLF describes the -er model as the productive conjugation: newly coined verbs almost always use it. This is a statement about productivity, not proof that no other group can ever gain a member. That framing changes what "irregular verb" means in French: the third group has relatively little productivity, and much of what looks unpredictable inside it turns out to cluster into families, not sit scattered at random. Spanish sorts its own irregular verbs by a different organizing principle entirely: the RAE groups Spanish irregular verbs by exactly what part of the stem changes, vowel, consonant, both, or the root itself, not by membership in some closed grammatical class. That classification cuts across frequency and conjugation class; the French three-group convention is a different way to organize paradigms.
Four common irregular examples: être, avoir, aller, faire
Être and avoir are the two verbs every French sentence in a compound tense eventually leans on, since they are also the auxiliaries behind passé composé and every other compound form. Per Larousse's conjugation tables, être runs je suis, tu es, il/elle est, nous sommes, vous êtes, ils/elles sont: six forms that share almost nothing with each other in sound or spelling, which is exactly what "truly irregular" means here. Avoir runs j'ai, tu as, il/elle a, nous avons, vous avez, ils/elles ont, a different but equally scattered set of stems.
Aller and faire complete these four examples. Aller, confirmed above as a third-group verb despite its -er ending, conjugates je vais, tu vas, il/elle va, nous allons, vous allez, ils/elles vont: the singular va- forms, all- in nous/vous, and v- in vont show stem alternation. Allons and allez retain the familiar -ons and -ez endings. Faire runs je fais, tu fais, il/elle fait, nous faisons, vous faites, ils/elles font. Vous faites belongs to a small, well-known exception: per Larousse, être (vous êtes) and dire (vous dites) take that same -tes ending instead of the -ez most other verbs use in the vous form. These four verbs are also among the handful that carry an irregular subjunctive stem, a different irregularity covered in full in the French subjunctive breakdown, where avoir and être turn out to be the only two verbs in the language that also swap their subjunctive endings, not just their stem. Être also sits behind a separate irregularity pattern with nothing to do with its own conjugation: it's the auxiliary French reflexive verbs always take instead of avoir, where the real complication isn't the auxiliary choice but when the past participle agrees with the subject and when it doesn't.
Most other "irregular" verbs are family patterns, not one-offs
Pouvoir, vouloir, and devoir share a stem-change shape old grammar guides nicknamed the "boot" or "shoe" pattern, because circling the changed forms on a conjugation chart traces that outline. Per Larousse, pouvoir runs je peux, tu peux, il/elle peut, nous pouvons, vous pouvez, ils/elles peuvent; vouloir runs je veux, tu veux, il/elle veut, nous voulons, vous voulez, ils/elles veulent; devoir runs je dois, tu dois, il/elle doit, nous devons, vous devez, ils/elles doivent. The singular and third-person plural forms differ from nous/vous, but their written bases are not identical: peu-/pouv-/peuv-, veu-/voul-/veul-, and doi-/dev-/doiv-. Learn that split once and it applies to the whole family, not just to whichever one verb happened to come up in a textbook exercise.
Venir and tenir have a related three-way alternation. Per Larousse, venir conjugates je viens, tu viens, il/elle vient, nous venons, vous venez, ils/elles viennent: vien- in the singular, ven- for nous/vous, and vienn- for ils/elles. Tenir follows the identical pattern (je tiens, nous tenons), and so does every compound built on either verb: revenir, devenir, tenir's own compounds like obtenir and retenir. Learning venir well effectively means learning a dozen other verbs at the same time.
Prendre works the same way on a third stem shape: je prends, tu prends, il/elle prend, nous prenons, vous prenez, ils/elles prennent, per Larousse, with apprendre, comprendre, and reprendre inheriting the identical prend-/pren-/prenn- split. Across all three families, the useful unit to memorize is the family's stem-change rule, not each individual compound verb. A flat alphabetized list of "top 100 irregular verbs" hides that relationship entirely, presenting reprendre and prendre as two unrelated entries to learn from scratch.
Verbs people call "irregular" that are actually fully regular
A separate category gets lumped in with irregular verbs by habit, even though it belongs entirely to the regular first group. Per Wikipedia's spelling-rule summary for -er verbs (checked 13 October 2026), appeler doubles l in j'appelle. Other -eler/-eter verbs may use a grave accent instead, with the 1990 spellings extending that pattern except to appeler, jeter, and their derivatives. In j'appelle, the doubled l signals that the preceding e is pronounced as in "elle," not swallowed the way it otherwise would be. Préférer and other -é[consonant]er verbs shift é to è under the same silent-ending condition: je préfère, nous préférons. Payer and other -ayer verbs may shift y to i before a silent e (je paie, alongside the still-standard je paye).
These verbs stay inside the regular -er pattern; a spelling adjustment sits on top of it purely to keep the written form matching the spoken one, and the spelling also records vowel alternations, as je préfère contrasts with nous préférons. Wikipedia notes one irregularity (checked 13 October 2026) inside this group that is not just spelling, and it is narrower still: envoyer (and renvoyer) takes an irregular stem specifically in the future and conditional (j'enverrai, not the expected "envoierai"), a real, isolated exception, not a spelling rule, and an example of why group membership alone does not make every form predictable.
Where the same irregular stems resurface: participles and the subjunctive
Irregularity in one tense does not automatically predict irregularity in another, but for these particular verbs it usually travels along. Être, avoir, and faire have participles été, eu, and fait, while aller forms allé with the ordinary -é pattern. Several of the family-pattern verbs have other participle endings: venir gives venu, tenir gives tenu, prendre gives pris (with apprendre and comprendre inheriting appris and compris the same way prend- carried across their present tense). The full set of irregular past participle families, sorted by ending group and not memorized verb by verb, covers this in more depth than fits here.
Several of the same high-frequency verbs, être, avoir, aller, and faire among them, also take an irregular stem in the present subjunctive, a distinct irregularity from anything covered above since the subjunctive is a different mood built on its own stem rules entirely. Que je sois, que j'aie, que j'aille, and que je fasse do not derive from any of the present-tense forms given earlier; the full account of which verbs break the subjunctive's otherwise uniform ending pattern, and which two break the endings themselves, lives in the site's dedicated subjunctive guide.
How to actually learn these verbs
Start with être and avoir: they are also the auxiliaries every compound tense in French is built on, so getting those two stem sets solid turns half of the compound-tense system into a matter of adding a participle rather than learning a new conjugation. Add aller and faire next; between the four of them, that covers the verbs that show up in nearly every conversation.
After that, the more efficient move is studying related stem patterns together: once venir is solid, tenir and their combined dozen-plus compounds are most of the way learned already; pouvoir also helps you recognize the related, but separately spelled, alternations in vouloir and devoir. Spend the least effort on spelling-change -er verbs like appeler or préférer: treating them like third-group irregulars wastes effort on something already fully predictable from a spelling rule.