There are a number of verbs in the past that are irregular. Here is a list of a few to start off with.
You will come across many more -
You have already come across the forms of IR (to go) in the preterite.
fui / fuiste / fue / fuimos / fuisteis / fueron
SER (to be) has exactly the same parts as IR.
Por ejemplo:
¿Adónde fuiste? (Where did you go?)
Fui a Marbella (I went to Marbella)
Fue estupendo (It was great!)
Other irregular preterites include the following -
| DAR (to give) | VER (to see) | HACER (to do) |
| Di | Vi | Hice |
| Diste | Viste | Hiciste |
| Dio | Vio | Hizo |
| Dimos | Vimos | Hicimos |
| Disteis | Visteis | Hicisteis |
| Dieron | Vieron | Hicieron |
Por ejemplo:
¿Qué viste? (What did you see?)
Mi padre hizo footing
Yo di una vuelta