Killara (/kɪˈlɑːrə/) is a suburb on the Upper North Shore of Sydney in the state of New South Wales, Australia. Killara is located 14 kilometres (8.7 mi) north-west of the Sydney central business district in the local government area of Ku-ring-gai Council. East Killara is a separate suburb and West Killara is a locality within Killara.

Killara is an Aboriginal word meaning permanent or always there. The name of the suburb was chosen when the railway line opened in 1899. James George Edwards was a representative of the people who requested a station be built here. The suburb was established as a "Gentlemen's suburb", designed so that there would be no commercial ventures in the area. For this reason, the suburb has very few shops in the original development.

Killara Post Office opened on 7 November 1904.

Killara later became the home of the architect Harry Seidler, whose home—designed by him and his wife Penelope in the 1960s—can still be seen in Kalang Avenue. It is sometimes known as Killara House and sometimes as Harry and Penelope Seidler House. The couple moved into the house on Harry Seidler's birthday in 1967. The garden contains a sculpture by the Los Angeles sculptor Eric Orr. The house is heritage-listed.

Marian Street Theatre played a significant role in the cultural life of the North Shore. The theatre is temporarily closed for renovation works since 2013, and a proposal was passed by the local council to redevelop the site into a multipurpose arts and cultural facility.

Killara has a number of heritage-listed sites, including:

Killara is home to a train station that connects to the T1 and T9 lines for routes to Berowra via Gordon, City via Gordon on the T1 or routes through North Shore via City on the T9.

The Pacific Highway is the main road thoroughfare through Killara.