The gorgeous actress stopped by "The Late Show with Stephen Colbert" on Tuesday, where she greeted the unsuspecting comedian with one passionate kiss.
Check out the video above to see Stephen's stunned reaction!
After the kiss, the duo took a seat and a visibly-shocked Colbert started wiping the sweat off his face.
"If I didn't do it then I'd never get to do it," the 70-year-old explained of her kiss decision. "I have been dreaming of doing that for about, you know, for about 15 years. So, I just grabbed my chance."
"I suddenly can't remember any questions...you know what you're doing," the "Colbert Report" alum said in shock. "You really know what you're doing. Thank you so much for being here. Can you imagine the number of people who are jealous of me right now?"
"Including me when I watch it!" Miren joked. "I'll be going 'Ugh, why didn't I do more?'"
"Well, I'll tell you what -- the night is young, Dame Helen," Colbert quipped.
Is it just us, or do these two have some serious chemistry?!
What do you think about the actress' kiss and the late night host's reaction? Sound off below and check out the gallery above to see more leading ladies then and now!