I made a couple of harridans from left-over Tyranid gaunt, warrior, and gargoyle pieces. These are quite imposing in Epic scale, being the size of very large flyers. In Epic Armageddon, these are war engines with 3 damage capacity.
A close-up of the first one - the wings are from Dark Eldar ravagers, which are slightly larger and seem to be more fitting than gargoyle wings.
I used a slightly different pair of ravager wings for the second harridan, to give it a different position in flight.
Here's a harridan next to one of the Tau Orca transports. It's suitably menacing air support for the Tyranids.
I have a bunch of Onslaught games Tyranid proxies too, for all the smaller creatures, and I've got some ideas for other Tyranid bio-titans. More to come soon...