Double Act is a children's novel by Jacqueline Wilson, written in the style of a diary, which features identical twins Ruby and Garnet.

Ruby and Garnet are 10-year-old identical twins living with their father and grandmother since their mother, Opal, died.

The two have always been close despite their differences—Ruby is sociable, headstrong, and dreams of being an actress, while introverted Garnet is content to let Ruby dominate their relationship.

Garnet starts off well in new school and works hard, but once she makes a new friend called Judy, Ruby sulks and ignores her twin.

Surprisingly, Rose is supportive, although her efforts are for nothing, Ruby plots and succeeds in them running away to London for the audition.

Ruby is disgusted by Garnet's descriptive and mature writing but remains confident they will both pass.

After making friends with someone she previously considered rather a bully, Ruby starts to realise that she and Garnet do not need to be the same, and do not have to do the same things, to be happy.

The television film was made in 2001 for Channel 4 and aired in 2002, starring Birmingham twins, Zoe and Chloe Tempest-Jones.

Publishers Weekly described it as "an unexceptional mix of familiar plot devices" and recommended it (or did not) for readers age 9 to 12.