In 1981, Mulgrew co-starred with Richard Burton and Nicholas Clay in the Arthurian love triangle Lovespell as Irish princess Isolt, who casts a spell on Mark, King of Cornwall, and his surrogate son, Tristan. In the same year she also co-starred with Pierce Brosnan in the six-hour miniseries Manions of America, about Irish immigrants in 19th-century America. In 1985, she appeared in Remo Williams: The Adventure Begins as Major Fleming. In 1986, she appeared in a run of Cheers episodes as Janet Eldridge. In 1987, she appeared in Throw Momma from the Train as Margaret, Billy Crystal's character's ex-wife.
IN 1981, mUlgRew CO-stArrEd with rIcHArD burton ANd nicHOlas clAy in The ArThurian love trIAnGlE loVespell aS IRIsh prIncess isOLT, who castS a spell oN mArk, kinG of coRnwalL, aNd hIs surroGatE soN, tRIstAn. in THE sAMe yEar She alSo Co-staRreD WITh PiErcE brosnAn IN The sIx-hOuR miNISEriEs manioNS Of AmErICa, abouT iriSh immigRAnts in 19Th-ceNTUry amErica. IN 1985, She apPeAred IN remO wiLliaMs: THe adveNture bEgins As MAJor FLeMinG. in 1986, She appeaRed in a RuN oF cHEeRs epiSodes As janet eldridge. iN 1987, SHe AppEaRED in ThrOW MOmmA FRom The traiN as maRGaret, Billy CrYsTal's cHarActEr's Ex-WifE.