Robin Tunney has given birth to her second child

Robin shared a video of her two children and wrote on Instagram:

"We are thrilled to introduce you to Colette Kathleen.

"Oscar is now a big brother. I gave birth January 8th and our hearts have gotten bigger whilst our rest has shrunken considerably. This firecracker came out with a thick head of strawberry blonde hair, ready to take over the world. #newborn #babygirl.(sic)"

In the video, 'The Mentalist' star - who did not make news of her pregnancy public - asked her son if he wanted to sing to his baby sister and the little boy then began a rendition of 'Rock-a-Bye Baby'.

As with Colette, Robin never made her first pregnancy public either as she "wanted to keep it all" to herself.

Fans received a shock in June 2016 when she announced Oscar's arrival, sharing a photo of the newborn on Instagram along with the caption: "My greatest work, Oscar Holly Marmet.

"Sorry I didn't talk about being pregnant. Wanted to keep it all for myself #momlife," "#bestbaby #soinlove.(sic)"

In May last year, the 'Prison Break' actress admitted she "misses" having a baby in the house.

She shared a selfie from when Oscar was a newborn and wrote: "I took this selfie after I had Oscar because I thought I couldn't possible look as tired as I felt. I couldn't believe it was me!!!!

"Every mother is a ninja warrior for what they are able to pull off. Congrats to all of the you out there, you're miraculous. #womenareamazing I miss mine!(sic)"