Many verbs in Spanish, especially common verbs like conocer, estar, haber, hacer, ir, poner, saber, tener, traer, and venir, are irregular in the present tense, as well as in some or all other tenses and moods. In many respects the irregularities of these verbs have similarities, although these characteristics are relatively unpredictable.
* Verbs that end in -cer or -cir, when these endings are preceded by a vowel, add the consonant -z in the first person singular of the present indicative and in all forms of the present subjunctive.
** The impersonal form of haber, which translates as
"there is" or "there are," has an additional irregular form which
is hay.
Many other verbs in Spanish that appear irregular are more
properly called "stem-changing" verbs or
verbs "with changes in
spelling."
Irregular verbs in the future and
conditional
Irregular verbs in the
imperfect
Irregular verbs in the preterite
Irregular verbs in the
subjunctive
Verbs