Justin Theroux has wished his ''fiercely loving'' ex-wife Jennifer Aniston a happy birthday.

The 'Leftovers' star paid tribute to his former spouse, dubbing her ''fierce, kind and funny.''

Taking to Instagram, he wrote: ''Happy Birthday to this fierce Woman. Fiercely loving. Fiercely kind ... and fiercely funny. [Love] you B (sic)''

Jennifer and Justin split in February 2018 but have remained friendly since they went their separate ways.

The 47-year-old actor had previously admitted he doesn't believe in having ''ex'' partners because he hopes all his former lovers can continue to be ''friends'' with him.

When asked if he thinks a relationship has ''failed'' once it's ended, Justin said: ''It's absurd to call someone 'my ex-girlfriend' or something ... To add an 'ex' to someone feels very strange. Idealistically speaking, she would still stay your friend. You know, nobody is inherently evil. Nobody. Except for those narcissistic and self-involved people - some of them are always on the news at the moment. 99 percent of the people aren't evil though, I don't think so. They don't wake up in the morning and think, 'How can I harm someone today?' No, what makes us human is the pursuit of happiness.''

The couple announced their split in a joint statement, where they said the focus would be on continuing their ''cherished friendship''

It read: ''In an effort to reduce any further speculation, we have decided to announce our separation. This decision was mutual and lovingly made at the end of last year. We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship. Normally we would do this privately, but given that the gossip industry cannot resist an opportunity to speculate and invent, we wanted to convey the truth directly. Whatever else is printed about us that is not directly from us, is someone else's fictional narrative. Above all, we are determined to maintain the deep respect and love that we have for one another.''