Is Catherine deneuve a lesbian

Nope. But she's played a lesbian in 2 different movies, and a bisexual in one other:

1. Zig Zig

2. The Hunger (as the bisexual vampire with Susan Sarandon) - which involved a pretty erotic, yet classy sex scene between the two actresses.

3. Les Voleurs (Thieves)

And here's a quote taken from an interview with The Advocate on the 25th July 1995:

"I cannot imagine having a physical relationship with a woman. I have not done that. But I really love women."

So, though she may be open to the idea, there's no evidence to suggest she's anything but heterosexual (sadly for some).