The sixth season of 'Game of Thrones' could prove to be the time to see previously absent characters coming back into action. In addition to Bran Stark finally showing what he learned from the Three-Eyed Raven and Rickon Stark hopefully returning from his vacation with the Umbers, an ally of Winterfell has reportedly been spotted on the set in Northern Ireland.

[SPOILERS AHEAD]

According to Watchers on the Wall, Clive Russell has been spotted in the 'Game of Thrones' set in Corbet. The actor, who portrays Catelyn Stark's uncle Brynden Tully aka The Blackfish, will reportedly be shooting scenes with Nikolaj Coster-Waldau, who plays Jaime Lannister. The two stars together with Jerome Flynn will be filming the Siege of Riverrun which has been mentioned in the fourth 'A Song of Ice and Fire' book 'A Feast of Crows.'

And it looks like the return of the Blackfish might also confirm a recent sighting of Michelle Fairley, who played Ned Stark's beloved until the fourth season of 'Game of Thrones.' It was recently reported that the actress was spotted in a Belfast coffee shop with a former costar, who a Twitter user confirmed played Cat's "father or uncle" in the show. There is a possibility that the fan had meant Clive Russell, which was confirmed by another Twitter user.

Although it was possible that Michelle Fairley and Clive Russell were just catching up and having coffee together, fans continue to speculate that her presence in Belfast (and in the company of a returning star) could mean that the cruel incarnation of Catelyn Stark will finally appear in 'Game of Thrones.'

Lady Stoneheart has long been expected to make an appearance in the TV series following the death of Catelyn Stark. The character's last appearance in George R.R. Martin's book series was also in the fourth novel, where she forces Brienne of Tarth to assassinate Jaime Lannister.

Will we finally encounter Lady Stoneheart? Find out when the sixth season of 'Game of Thrones' premieres on HBO on April 2016.