Yes, STRANGLER is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, R 1, A 1, N 1, G 2, L 1, E 1, R 1.

Is it a valid word?

STRANGLER is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an epiphytic vine or tree whose aerial roots extend down the trunk of a supporting tree and coalesce around it eventually strangling the tree
someone who kills by strangling

Also: strangler tree.

Not playable in Scrabble US: GARROTTER.