Eating green algae

Snails- just about any... Nerites famous for algae appetite.
Shrimp- again, the loose green algae any will eat. Amanos supposedly the best at this (you will need to still feed your shrimp)- they're all supposed to partake of the green though.
Fish- Plecos; some plecos better than others; Otto Cats; Siamese Algae eaters (whilst young); Mollies (if hungry enough); Flying foxes. Many fish will eat algae if they're starving- but would prefer not (I'm not suggesting you starve your fish to get rid of Algae)

Be ware of Chinese Algae eaters (or Algae eaters; if type not specified it's usually the CAE) - these turn into nasty little critters that attack your other fish as they age. Back when I was young and naive I had two CAE- stressed every other fish in the tank to death.

I would go with otos, they especially love green algae, but you would have to supplement if they ate it all and not enough grew back.

what size tank and inhabitants?

I would get some nerites to add to your clean up crew, they would do a great job at it.

Kristina

chunks talk to msjinkzd, the lady is the queen of snails

I would recommend finding the cause of the large amounts of algae and fixing that as opposed to adding stock.