Eureka
Furude Rika
Mihama Chiyo
Nagi
Sanzenin Nagi
Tsukamoto Tenma
Pedo bear
Koiwai Yotsuba
Hatsune Miku
Hirasawa Yui
Rebecca Miyamoto
Yoko Littner
Izumi Konata
Suzumiya Haruhi
Shana

Pedobear would definitely approve of this Christmas crossover
Added notes for the girls, not sure about the pets.
The cat on the mantle is from Lucky Star. It's shown between the first and second halves of the episodes and right before the Lucky Channel segment. I don't think it has a name.