The latest episode of long-running fantasy series Supernatural just featured an easter egg that would have had generated feverish excitement among the Walking Dead fandom.

The opening shot of season 12 episode 'Somewhere Between Heaven and Hell' saw lead character Dean (Jensen Ackles) holding Lucille, the barbed-wire-wrapped baseball bat that famously belongs to Jeffrey Dean Morgan's malevolent Saviours' leader Negan in the AMC zombie series.

Fans of both US dramas would no doubt recall that Morgan appeared in Supernatural as John Winchester, the father of lead characters Sam (Jared Padalecki) and Dean which is what makes the cameo even sweeter: as he is showing holding the bat, he says: “Dad used to love this thing.”

Naturally, fans of both shows expressed their excitement via Twitter.

In The Walking Dead, Negan used Lucille to beat two fo the show's lead characters to death in the traumatic season seven premiere.

Supernatural star Jensen Ackles has previously teased that the two series share a universe.