Danny Glover Danny Glover

As How I Met Your Mother wraps up its fourth season, fans can expect to get drop-ins from faces both familiar and new.

From the latter category, Danny Glover will turn up "in an interesting way," series cocreator Carter Bays tells TVGuide.com.

Hmm, could it be that Barney and his brother James (played here and there by Wayne Brady) have — gasp — different fathers? "Boy, I wish had thought of that a month ago!" Bays says upon hearing our suggestion. "That's much better than what we came up with." Oh, we highly doubt that.

Glover's Mother visit comes on the heels of the Lethal Weapon star scoring a role on My Name Is Earl, as Crab Man's daddy. He also wooed Sally Field last season on Brothers & Sisters.

In addition to "a couple other" such guest castings on the horizon, Bays promises that fans will "see some old favorites come back — people that you haven't seen in a while — which will be fun."

And on top of it all? Bays hints at "a cool surprise" that will lead us ever closer to a certain Mother, saying, "The last few episodes will address the title of the show."