List of Spanish Irregular Verbs:

When the last syllable is a vowel  (u -> ú)

acentuar (to stress/ to accent)

actuar (to act)

conceptuar (to consider/ to judge)

continuar (to continue)

extenuar (to exhaust/ to drain)

insinuar (to insinuate)

perpetuar (to perpetuate)

When the last syllable is a vowel  (i -> í)

fotografiar (to take a photograph of)

agriar (to turn sour)

confiar (to confide)

criar (to breed)

desvariar (to be delirious/ to talk nonsense)

enviar (to send)

espiar (to spy on)

esquiar (to ski)

liar (to tie up/ to wrap/ to roll)

When we add an e to the last letter of the stem c then  (c -> qu)

platicar (to chat)

mascar (to chew)

electrificar (to electrify)

clarificar (to clarify)

aparcar (to park/ to shelf)

suplicar (to plead)

justificar (to justify)

blocar (to block)

complicar (to complicate)

cualificar (to qualify)

certificar (to confirm)

edificar (to build)

fabricar (to manufacture/ to build/ to make)

explicar (to explain)

falsificar (to forge)

intensificar (to intensify)

marcar (to mark)

mascar (to chew)

picar (to bite)

provocar (to incite)

refrescar (to refresh/ to chill)

sacar (to take out)

tocar (to touch/ to play on an instrument)

unificar (to unite)

When we add an e to the last letter of the stem z then  (z-> c)

aterrorizar (to terrorize)

abrazar (to embrace)

amordazar (to gag/ muzzle)

adelgazar (to lose weight)

aterrizar (to land)

analizar (to analyze)

alcanzar (to reach)

civilizar (to civilize)

alzar (to lift/ raise/ hoist)

cazar (to hunt)

cotizar (to quote/ to price)

generalizar (to spread/ to generalize)

gozar (to enjoy)

lanzar (to throw/ to fling)

memorizar (to memorize)

punzar (to prick/ to stab)

rozar (to rub/ to brush/ to graze)

utilizar (to use)

When we add an a or o to the last letter of the stem g then  (g -> j)

escoger (to choose)

acoger (to welcome/ take in/ receive)

coger (to take)

encoger (to shrink)

recoger (to pick up)

When we add an e to the last letter of the stem g then  (g ->gu)

castigar (to punish)

agregar (to add)

apagar (to put out/ to put off/ to extinguish)

chocar (to crash)

fatigar (to tire/ to weary)

halagar (to flatter)

juzgar (to judge)

llegar (to arrive)

madrugar (to get up early)

tragar (to swallow)

When we have an e in an accented syllable then  (e -> ie)

alentar (to encourage)

atender (to attend to)

calentar (to heat up/ to warm up)

comenzar (to start/ to begin)

confesar (to confess)

defender (to defend/ to stand up for)

descender (to go down)

despertar (to wake/ to arouse)

empezar (to begin/ to start)

encender (to light/ to inflame)

encerrar (to shut up/ to shut in)

extender (to stretch out)

mentar (to mention)

pensar (to think)

perder (to lose)

quebrar (to break)

sentar (to sit/ to seat)

When an o occurs in a stressed syllable then  (o -> ue)

acordar  (hacer algo) (to agree to do something)

acostarse (to go to bed)

aprobar (to approve)

concordar (to agree/ to reconcile)

contar (to count/ to tell)

costar (to cost)

desaprobar (to disapprove of/ to reject)

descontar (to deduct)

encontrar (to find/ to encounter)

engrosar (to swell)

mostrar (to show)

recordar (to remember)

tronar (to thunder)

devolver algo (to give something back)

disolver (to dissolve/ to break up)

doler (to hurt)

envolver (to wrap up/ to wind)

llover (to rain)

morder (to bite/ to eat into)

When an o occurs in a stressed syllable then  (o -> ue) or  (o -> u)

dormir (to put to bed)

dormirse (to go to bed)

morir (to die)

When an o occurs in a stressed syllable then  (e -> ie) or  (e -> i)

consentir (to allow/ to permit)

digerir (to digest/ to assimilate)

divertir (to entertain/ to amuse)

hervir (to boil)

invertir (to reverse/ to invert)

mentir (to lie)

preferir (to prefer)

referir (to tell/ recount)

No pattern followed for this verbs whose e becomes I  (e -> i)

henchir (to fill/ to fill up)

expedir (to send/ to dispatch/ to issue)

impedir (to prevent)

pedir (to ask for/ to order)

When we add an a or o to the last letter of the stem c then  (c ->zc)

agradecer (to thank)

amanecer (to dawn)

compareceer (to appear)

aparecer (to appear/ show up)

crecer (to grow)

decrecer (to decrease/ to decline)

conocer (to know)

When we add an  (a/ e/ o) then  (u -> ü)

aguar (to water down)

apaciguar (to calm down)

atestiguar (to testify to)

averiguar (to find out)

fraguar (to forge)

No pattern followed here  (ui->uy)

construir (to build/ manufacture)

confluir (to converge/ to meet)

contribuir (to contribute)

derruir (to demolish/ to knock down)

destituir (to dismiss)

destruir (to destroy/ to wreck/ to demolish)

diluir (to dilute)

disminuir (to reduce/ to decrease)

distribuir (to distribute)

fluir (to flow)

incluir (to include)

influir (to influence)

reconstruir (to rebuild/ to reconstruct)

rehuir (to avoid)

Miscellaneous Irregular verbs (usually no pattern followed)

andar (to walk)

desandar (to go back over/ to retrace the trail)

caer (to fall)

recaer (to relapse)

dar (to give)

decir (to say)

estar (to be )

deshacer (to undo/ to unpack/ to destroy)

hacer (to do/ to make)

rehacer (to do again/ to rebuild)

satisfacer (to satisfy/ to quench)

ir (to go)

oír (to hear)

poder (to be able to)

querer (to want)

saber (to know)

salir (to go out)

prevaler (to prevail)

valer (to value)

Traer family

contraer (to contract/ to acquire/ catch)

distraer (to amuse/ to entertain)

extraer (to extract)

maltraer (to maltreat)

traer (to bring)

Tener family

abstenerse (to abstain)

contener (to contain/ to restrain/ to hold back)

detener (to arrest/ to stop/ to hold up/ to delay)

obtener (to get/ to win)

sostener (to support)

Venir family

convenir (to be suitable)

devenir en (to become/ to turn into)

intervenir (to take part/ to get involved)

prevenir (to prevent)

provenir de (to come from)