In the UK we call them Romanians. (Oops, scratch that, I didn't say it, sorry Romanians).
Seriously, though, we welcome around 665000 legal immigrants* to the UK every year (around 310000 leave, so we have a net inflow of er, quite a lot). The vast majority work and contribute culturally, economically and intellectually to UK society.
And there are also some that don't. And they seem always to come from the same few countries.
*We do not really know how many illegal immigrants there are, but usually reckoned to be at least another 100000.