In OOT, you can get Masks. You do not need them to beat the game since they are a sidequest, but they are fun to get. Here is a list of the 8 masks:

Keaton Mask- The Keaton Mask is the first mask you can buy from the Happy Mask Shop in Hyrule Castle Town. The shop is closed until you show the letter from Zelda to the guard blocking the way up Death Mountain Trail. After the Guard opens the trail up, the Happy Mask Shop opens. Buy the Keaton Mask there. Then go back to the guard you showed the letter to and sell him the mask. You will make a bit of money.

Skull Mask-The second mask that you can buy from the Happy Mask Shop. Buy it and travel to the Lost Woods, where you will find a Skull Kid. Put on the mask and talk to him, and he asks you for it. You must give him the Skull Mask, even though you will lose money on the transaction.

Spooky Mask- The third mask that you can buy from the Happy Mask Shop. Buy it and head to Kakariko Graveyard. There is a boy there who wants to be like his hero, Dampe, but he's too small and cute for the job and wants the mask to look scarier. Sell it to him for the same price you bought it- you don't gain or lose on this transaction.

Bunny Hood- The fourth mask that you can buy from the Happy Mask Shop. Head out of the castle into Hyrule field during the day. Go by Lon Lon Ranch and look for a running man. He's hard to find and catch, but once you find him put the mask on and talk to him. In return, he gives you a huge rupee that fills up your wallet! You make money on this transaction, obviously.

After you sell the Bunny Hood, there are 4 new masks that appear in the Happy Mask Shop. You cannot buy them, but you can borrow them for free. They are:

The Mask of Truth- When wearing this mask, you can talk to Gossip Stones across the world to learn secrets, clues, and... gossip.

Gerudo Mask- When you talk to people while wearing this mask, will make other people around Hyrule give you different responses than they normally do.

Goron Mask- When you talk to people while wearing this mask, will make other people around Hyrule give you different responses than they normally do.

Zora Mask- When you talk to people while wearing this mask, will make other people around Hyrule give you different responses than they normally do.